But why?
Probably because having two separate dependency management solutions can lead to a lot of needless headaches.
And it makes particular sense for Gnome to switch over, since Gnome is focused on user space apps. Flatpaks should generally be more relevant and lower risk, long term, since they don't require root privileges to install.
Good news!
Boox will run any cloud sync that has a recent Android app available. It's just an Android tablet, at heart, and it's already unlocked.
In particular, the local NAS sync client for Synology runs like a dream.
Edit: Oops. I missed that we switched from Boox to reMarkable, there.
I guess I'll leave this since Boox sells eInk tablets that are feature matched to reMarkable, anyway.