Admittedly not familiar with Mobian - I think the biggest differences are that postmarketOS is based on Alpine Linux (and musl in turn) and encourages porting t

Admittedly not familiar with Mobian - I think the biggest differences are that postmarketOS is based on Alpine Linux (and musl in turn) and encourages porting to a wide variety of devices, while Mobian builds on Debian and attempts to provide more complete support for a smaller number of phones