As far as I understand things there is no current way to make a working TVheadend server within Android or Linux which supports the dTV board. The reason is that TVheadend relies on a Linux infrastructure of DVB driver support (LinuxTV project). As such all the possible sat drivers present themselves to TVheadend in a consistent way and the drivers all conform to a Linux standard format.
There is a ported APK of TVheadend available for the Nvidia Shield running Android which might run on other Android devices - but it needs the drivers to be formatted in a similar way to the Linux version of TVheadend.
The issue is that the way that the VTV program implements access to the dTV board is via a proprietary binary driver hacked into a dedicated APK program for Android TV. This driver is not compliant with either the Android TVheadend driver format or the LinuxTV dvb driver format. Since the APK is closed source it is difficult for anyone to port the driver into either the Android TVheadend driver format or the LinuxTV driver format. This is the main limitation of Android overall - it doesn’t conform to Linux standards (even though it is a form of Linux) and there is no obligation on any Android programmer to release their source code to make its porting easier. In fact the culture in ARM world is to not make it easy for the Open Source community to access their hardware.
The good news is that Khadas and FrankTV have sent a sample to a Libreelec developer who has already reverse engineered a driver for the similar hardware found within the MeCool KIII pro . it should be possible for him to make a small adjustment to his driver to make it work with the VIM2. At that point it would be possible to easily port the driver to a general Linux build and even the APK of TVheadend running in Android.
Your best bet is to wait for him to receive the board and release the driver and then run a version of Libreelec with the driver support.
The VTV software baked into the various Nougat ROMs offered by Khadas do not have any AC3 license support, which means that a substantial subset of all SAT channels will have no audio and no way to add the AC3 support. The VTV software is flawed by design. Again the good news is that Libreelec do’s a software based transcode of AC3 streams which means that they work with Libreelec and TVheadend.
Android is a waste of time as a serious media player and I think Khadas could have done more to make sure that their products worked better in Linux out of the box or at the very least offered a way to add AC3 support to Android.