To be fair, all of that was in the course of less than a week, and I neither heavily use nor customize my personal laptop, so it's likely that if there are issues, I didn't encounter them.
Even so, I was quite impressed with how simple and seamless it was for me.
I installed kinoite on my laptop. Rebased to silverblue for a while to try out gnome, rebased to kinoite rawhide to check out kde plasma 6, then back to kinoite 39. I think a few minor settings had to be redone, but no real issues.
I've used both, and the only third party repo I've enabled was tailscale. I've not had any issue with needing codecs in anything I've Installed through the discover app. I'll admit that I don't have an Nvidia card, so I don't know how good support is ootb there (though iirc, at least openSUSE has a separate installer that include Nvidia drivers)
I think your best bet for this is one of the spinoffs of enterprise Linux: fedora or openSUSE. both are very solid ootb, and have starting configurations that are generally good.
The microos or silverblue variants respectively are really promising as well, but still have some caveats.
Good luck! I've been very happy with my microos installs. I've got kalpa on my desktop and aeon on my laptop. I'm following a project that uses a microos base for the Steam Deck too (which is ironic since the steam deck is what made me aware of read only root Linux and flatpak in the first place).
I didn't, libraries are stored in different places in flatpak vs native install. You could probably add the normal install location in the flatpak using flat seal, but having the install directory in /home (the default for flatpak) was fine for me .
For what it's worth, I'm using steam in flatpak in microos now, and it's been mostly seamless
I did this for a short while and didn't run into any issues. They have their own separate libraries, though you could change that if you wanted to though.
This analysis is spot on