Wayland and GPU stuff should be very good in endeavor, better than most systems I have seen, better than openSUSE leap and mint certainly. I don’t know fedora however.

Endeavor has its own base repo, but also the regular arch stuff like aur. The AUR is probably the best source for all those programs that are usually missing in your repo, and since the base stuff is stable in endeavor there is no problem if some random program needs a special version or a manual install sometimes, it won’t affect anything else.
The AUR is not the main package source for endeavor.
I don’t know your hardware, but the combination of up to date system components, endeavors focus on just working, and all the shit in the aur (to my understanding flatpak is currently quite useless for drivers) sound like it should just accept any hardware at least as well as other linux distros.

On a sidenote for flatpaks. There is this long running conflict between stability, portability, and security. The old-school package systems are designed to allow updating libraries systemwide, switching-in abi compatible replacements containing fixes. On the other hand, you have appimage, flatpak, …, which bring their own everything and will therefore keep running on old unsafe libraries sometimes for years before the developers of all those specific projects update their projects’ versions of all those libraries.