Tvheadend

There are two different versions of this USB-dongle. If bought from China ie. Aliexpress, you have to try other .fw's.

Make a backup of your original files. (dvb-demod-si2168-b40-01.fw and dvb-tuner-si2158-a20-01.fw)
Copy these two attached files to your /lib/firmware folder, and add their corresponding rights. (chown root.root or whatever your other fw files are)

Then restart and try again.

Yes indeed i bought my stick from Aliexpress, so there must be some firmware issues i guess.
I copied the firmwares to the folder and adjusted the owner:

laurenz@laurenz-BHYVE:/lib/firmware$ ls -al |grep dvb-
-rw-rw-r--  1 root root    6919 Sep 20 12:37 dvb-demod-si2168-b40-01.fw
-rw-rw-r--  1 root root    5015 Sep 20 12:37 dvb-tuner-si2158-a20-01.fw

But still Tvheadend is unable to find any data on the muxes.
Here is what my dmesg looks like:

laurenz@laurenz-BHYVE:~$ dmesg |egrep "firmware|dvb|frontend|usb" 
[    0.375126] usbcore: registered new interface driver usbfs
[    0.375126] usbcore: registered new interface driver hub
[    0.375126] usbcore: registered new device driver usb
[    1.024066] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 5.04
[    1.024068] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[    1.024069] usb usb1: Product: xHCI Host Controller
[    1.024070] usb usb1: Manufacturer: Linux 5.4.0-47-generic xhci-hcd
[    1.024070] usb usb1: SerialNumber: 0000:00:05.0
[    1.026800] usb usb2: We don't know the algorithms for LPM for this host, disabling LPM.
[    1.026816] usb usb2: New USB device found, idVendor=1d6b, idProduct=0003, bcdDevice= 5.04
[    1.026817] usb usb2: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[    1.026817] usb usb2: Product: xHCI Host Controller
[    1.026818] usb usb2: Manufacturer: Linux 5.4.0-47-generic xhci-hcd
[    1.026819] usb usb2: SerialNumber: 0000:00:05.0
[    1.028886] usb usb3: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 5.04
[    1.028887] usb usb3: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[    1.028888] usb usb3: Product: xHCI Host Controller
[    1.028889] usb usb3: Manufacturer: Linux 5.4.0-47-generic xhci-hcd
[    1.028889] usb usb3: SerialNumber: 0000:00:1e.0
[    1.029331] usb usb4: We don't know the algorithms for LPM for this host, disabling LPM.
[    1.029345] usb usb4: New USB device found, idVendor=1d6b, idProduct=0003, bcdDevice= 5.04
[    1.029346] usb usb4: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[    1.029347] usb usb4: Product: xHCI Host Controller
[    1.029347] usb usb4: Manufacturer: Linux 5.4.0-47-generic xhci-hcd
[    1.029348] usb usb4: SerialNumber: 0000:00:1e.0
[    1.241541] usb 4-1: new SuperSpeed Gen 1 USB device number 2 using xhci_hcd
[    1.263714] usb 4-1: New USB device found, idVendor=fb5d, idProduct=0001, bcdDevice= 0.00
[    1.263715] usb 4-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[    1.263716] usb 4-1: Product: HID Tablet
[    1.263717] usb 4-1: Manufacturer: BHYVE
[    1.263718] usb 4-1: SerialNumber: 01
[    1.269371] usbcore: registered new interface driver usbhid
[    1.269372] usbhid: USB HID core driver
[    1.271274] input: BHYVE HID Tablet as /devices/pci0000:00/0000:00:1e.0/usb4/4-1/4-1:1.0/0003:FB5D:0001.0001/input/input4
[    1.271472] hid-generic 0003:FB5D:0001.0001: input,hidraw0: USB HID v10.01 Mouse [BHYVE HID Tablet] on usb-0000:00:1e.0-1/input0
[    1.353820] usb 1-4: new high-speed USB device number 2 using xhci_hcd
[    1.507195] usb 1-4: config 1 interface 0 altsetting 0 bulk endpoint 0x86 has invalid maxpacket 188
[    1.509878] usb 1-4: language id specifier not provided by device, defaulting to English
[    1.517437] usb 1-4: New USB device found, idVendor=0572, idProduct=c688, bcdDevice= 8.00
[    1.517439] usb 1-4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[    3.444544] usb 1-4: dvb_usb_v2: found a 'MyGica Mini DVB-T2 USB Stick T230' in warm state
[    3.445317] usb 1-4: dvb_usb_v2: will pass the complete MPEG2 transport stream to the software demuxer
[    3.445324] dvbdev: DVB: registering new adapter (MyGica Mini DVB-T2 USB Stick T230)
[    3.445328] usb 1-4: media controller created
[    3.451548] dvbdev: dvb_create_media_entity: media entity 'dvb-demux' registered.
[    3.568580] si2168 0-0064: firmware version: B 4.0.2
[    3.606429] usb 1-4: DVB: registering adapter 0 frontend 0 (Silicon Labs Si2168)...
[    3.606436] dvbdev: dvb_create_media_entity: media entity 'Silicon Labs Si2168' registered.
[    3.670477] rc rc0: MyGica Mini DVB-T2 USB Stick T230 as /devices/pci0000:00/0000:00:05.0/usb1/1-4/rc/rc0
[    3.670900] rc rc0: lirc_dev: driver dvb_usb_dvbsky registered at minor = 0, scancode receiver, no transmitter
[    3.670932] input: MyGica Mini DVB-T2 USB Stick T230 as /devices/pci0000:00/0000:00:05.0/usb1/1-4/rc/rc0/input5
[    3.673456] usb 1-4: dvb_usb_v2: schedule remote query interval to 300 msecs
[    3.673460] usb 1-4: dvb_usb_v2: 'MyGica Mini DVB-T2 USB Stick T230' successfully initialized and connected
[    3.673497] usbcore: registered new interface driver dvb_usb_dvbsky
[    4.758682] si2168 0-0064: downloading firmware from file 'dvb-demod-si2168-b40-01.fw'
[    5.542179] si2168 0-0064: firmware version: B 4.0.11
[    5.547842] usb 1-4: DVB: adapter 0 frontend 0 frequency 0 out of range (48000000..870000000)

It still does not download any firmware for the tuner, just for the demodulator. Is this normal?

I've just tried out my old TV-box with coreelec installed on it and checked the dmesg with the T230 attached.
There they look like this:

[    4.640511@0] usb 1-2: New USB device found, idVendor=0572, idProduct=c688
[    4.640516@0] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[    4.642026@0] usb 1-2: Unsupported device
[    6.747033@1] Registered firmware driver success.
[    6.747876@1] load firmware size : 76288, Name : video/h264_enc.bin.
[    6.749393@1] load firmware size : 1816576, Name : video/video_ucode.bin.
[    8.129923@1] dvb-usb: found a 'Mygica T230 DVB-T/T2/C' in warm state.
[    8.376871@1] dvb-usb: will pass the complete MPEG2 transport stream to the software demuxer.
[    8.377915@2] dvbdev: DVB: registering new adapter (Mygica T230 DVB-T/T2/C)
[    8.377933@2] usb 1-2: media controller created
[    8.378555@2] dvbdev: dvb_create_media_entity: media entity 'dvb-demux' registered.
[    8.403121@0] si2168 5-0064: firmware version: B 4.0.2
[    8.425092@1] usb 1-2: DVB: registering adapter 0 frontend 0 (Silicon Labs Si2168)...
[    8.425108@1] dvbdev: dvb_create_media_entity: media entity 'Silicon Labs Si2168' registered.
[    8.483492@3] input: Mygica T230 DVB-T/T2/C as /devices/platform/ff500000.dwc3/xhci-hcd.0.auto/usb1/1-2/rc/rc0/input7
[    8.484560@1] rc rc0: Mygica T230 DVB-T/T2/C as /devices/platform/ff500000.dwc3/xhci-hcd.0.auto/usb1/1-2/rc/rc0
[    8.484569@1] dvb-usb: schedule remote query interval to 100 msecs.
[    8.484671@1] dvb-usb: Mygica T230 DVB-T/T2/C successfully initialized and connected.
[    8.484757@1] usbcore: registered new interface driver dvb_usb_cxusb
[   10.594990@1] dvb-usb: recv bulk message failed: -110
[   10.866009@2] si2168 5-0064: downloading firmware from file 'dvb-demod-si2168-b40-01.fw'
[   12.591534@2] si2168 5-0064: firmware version: B 4.0.25
[   12.629545@3] si2157 6-0060: downloading firmware from file 'dvb-tuner-si2158-a20-01.fw'
[   13.814303@2] si2157 6-0060: firmware version: 2.1.9
[   13.814375@1] usb 1-2: DVB: adapter 0 frontend 0 frequency 0 out of range (48000000..870000000)

As you can see the firmware for the tuner gets loaded here.
I've checked the md5 sum of the firmware file on the coreelec box and the one that you sent me and they are exactly the same.

So I guess the firmware-file is the correct one that, but just doesn't get loaded correctly...?

Also what's weird is, that in the Tvheadend web interface of the coreelec box the T230 Stick is also detected as ATSC-C capable, that's not the case for the webinterface of Tvheadend in my VM.

The files I added, was taken from my working system of LibreElec, since I never got the other ones to work.

Did you manage to scan the muxes on your coreelec box, with the T230 stick?

Yes I did, under coreelec the scan works just fine.

That's why I'm confident, that eventually I will geht this to work under the Ubuntu vm too.

Since you've checked the files, and got them to work in coreelec system, I think there would be something wrong with your passthrough settings.

Yes seems so, maybe I should ask in the Truenas forums why the firmware for the tuner doesn't get loaded.
I can't think of a reason why it should work under coreelec but not under Ubuntu