Both the Pinephone and the Pinebook Pro recently received mainline Linux kernel support with version 5.7. Debian recently added support for the Pinebook Pro as well as the RockPro64. They have daily builds available here for most of Pine 64's devices: https://d-i.debian.org/daily-images/arm64/daily/netboot/SD-c.... There's no Pinephone build yet but IMO it's only a matter of time. That being said, "Mobian" is just a DEBOS recipe with some custom software included that a user by the name of A-Wei has been maintaining. You could clone their repo and build it yourself if you'd like, it's super polished! Here's the Mobian repo: https://gitlab.com/mobian1/mobian-recipes