And sometimes recommended by Microsoft support.

As far as I can see, it’s freeware, not foss

GrapheneOS said they are working with an unnamed OEM to make devices compatible with GOS. Hopefully they are good, because Pixels may indeed be a dead end.

You can probably expect GOS support as long as Google supports the device, that is the main limitation. For the newer Pixels that is promised to be 7 years after release.

Going by this table, Pixel 6 is currently the oldest to get full GOS updates

That matches Google’s software support

I’m not sure what a flatpak version could possibly do any better than the version I use.

The official OBS flatpak supports more codecs and integrations than some distro packages.

Stability is also a factor, especially on rolling or cutting edge distros. Fedora RPM release of Blender did not work for me at all with an nvidia GPU, for example.

AFAIK no systemd -> no flatpak -> don’t recommend to newbs. Say what you will about flatpak, but it is the official distribution method for some popular pieces of software and large GUI software generally works better through it (in my experience) - think Blender, GIMP etc.