[djsumdog]

The same way my Gentoo and Void Linux boxes are .. except touch interfaces of search and install (like F-Droid) instead of emerge/xbps-install/apt-get/yum, etc. F-Droid also allows 3rd party repositories, just like other Linux package managers (and unlike Google/Apple/Microsoft).

I guess you could also have non-free repos and some kind of payment API (does Ubuntu/Snap do this?) but I really want to see if I can just write apps for the gaps I find when trying to use a PureOS or KDE Plasma device.

edit: see some comments on permissions. Honestly I've not looked into this space very much. I assume there might need to be some cgroup isolation that can be used to lock off hardware and filesystems, similar to containers (not sure if Snap/Flatpak use cgroups).

I suppose malicious code could get in and spy on you, but we've got the same concerns on Linux desktops and official package repos. I don't know exactly ... there's a lot to think about there.