That was already clear to me but everything on the host is not persistent across reboots.
You have to add that somewhere in /boot/config and run:
bash /boot/config/sundtek_netinst.sh -dockerhost
on every reboot, you can put that for example in the go file (/boot/config/go <- but please be careful with it since it basically starts the WebUI and everything else from Unraid at the end of the boot process, preferably I would put that before emhttp starts).
What does the -dockerhost option exactly? Does it need to download something from the Internet or does it simply create the devices?
As mentioned above, the easiest solution would be to create a plugin for that because then the users can download it from the CA App <- all applications for Unraid (Docker templates and Plugins) and don't have to worry about anything, then I think it would be also possible to install the driver on the host and the users can pass through the /dev/dvbX devices to the container as usual.
I will maybe pick up the DVB-C adapter that is available on the used market near me.