I agree with the "interface at least as good as stock Android" part. I wouldn't even mind if someone re-created the Android UI with native GNU/Linux libraries instead of the ones from Android.
As long as the user choose the interface, this would surely make it easier for people to switch from Android to postmarketOS and users who'd like to use something different could freely do so.
Wait, I did not say that it needs to be compatible with anything. Just recreating the top bar, that you can drag down to connect to your Wi-Fi etc. and the three buttons at the bottom working in a similar way would make it very easy to migrate without any compatibility requirements.
But as ocdtrekkie has noted:
> At the point where the phone OS can't make calls yet, worrying about style is a bit premature.
This project looks awesome btw and keep up the work. When I read through it, I saw it more as just running plain Linux on your old Android devices; turning them into what you would normally use a Pi/Beagle Board for. I'd love to be able to turn old Android phones into small Linux machines, and not have all the Android rubbish.
As long as the user choose the interface, this would surely make it easier for people to switch from Android to postmarketOS and users who'd like to use something different could freely do so.