I started to build a "compact" handheld RasPi 3B+, but the driver situation for all the shield-like display assemblies I could find (including the promising-looking one I gambled on buying) was very poor. The best I could find was "download our special build of Raspbian", which is a showstopper for my priorities.

If there shield-like RasPi touchscreen open source drivers, mainlined in Linux, and also included in Raspbian and Debian, I'd like to hear of it.

(Blob-free would also be nice, though the RasPi itself has blob problems, so isn't as good as it could be for open source.)