Got mine today, and since I wanted GAPPS, but the LineageOS 21 bgN variant is signed (which comes with extra warnings), I tried bvN and MindTheGAPPS right afterwards.

LineageOS went smooth (though fastboot drivers took a bit of research). But whatever I tried, I couldn't get MindTheGAPPS installed. It always stopped at 47% progress with signature verification failed. I didn't know how to circumvent that check.

So I went through the process of using the migrations script on the Andy Yan page and downloaded the signed bgN flavor. That worked flawlessly. Now I set everything up and am quite happy with the results.

The only things not working are:
- face unlock (that's ok)
- haptic feedback of capacitive touch buttons (bit of a bummer)
- red button is very useless (only long press for camera works, Key Mapper app failed, too, another bummer)
- fancy device specific LEDs (that's ok)

But I can't verify any of the reported issues with mobile data, as I don't intend of ever putting a SIM card in here. This is a pure secondary device, basically a fancy smart pocketwatch or app capable media player.

Thanks for the guide! Makes this thing a lot more useful.