Linux

Try openSUSE Tumbleweed

Fedora KDE, Kinoite, or Nobara could all be of interest to you

check out Endeavour OS

Nobara, it's literally all the things you mentioned above

Throwing Debian in there. Switched from arch 6 months ago. Still running x11 because xfce doesn’t support wayland yet, but KDE does. I run amd cpu and gpu and have no compatibility issues. And with lutris/bottles/proton games run with minimal issues. Plus most every is based on Debian, so why not just use the original.

Arch is great, I'm using Plasma on Wayland and it works really well.

What about Arch (BTW)? You can decide exactly what do you want to have there.

Bleeding edge packages are great for gaming, and it supports everything else.

Pretty much every distro supports flatpak and butterFS and for most of them, there's a plasma wayland variant.

If you want to learn a bit about linux in general and the things that you might care about when picking a distro in the future, do a manual arch installation. There's an install script, but you still need to know exactly what you're doing. It just does the steps outlined in the installation guide for you.

Arch is also one of the best distros for gaming because it gets new updates first, which is great when game updates break something and your OS already has the fixes for it.

Don't laugh, hear me out...

Slackware current (rolling release)

Then switch to LTS version at the next release, which I'm thinking will happen before the end of the yeay.

It checks all of your boxes and will give you a different take on Linux computing.

NixOS, it has some learning curve, but your configuration is stored in git so you can always access any solutions you have employed at any point or any packages you used before

Of course, that also means you can roll back easily and there's also reproducible builds

It is completely different, so worth checking out even as a package manager

Gentoo 😉

EndeavorOS or Arch.

I would recommend Fedora Kionite, or uBlue KDE/ Bazzite. It's the same as Kionite, but preconfigured with some additional QOL-stuff. Bazzite is the equivalent to Nobara, but also immutable.

I turned into a huge fan for Silverblue (and spins) over the last few weeks.

Especially interesting is the Universal-Blue-project, which offers many "spins" (or to be more precise, new-interpretations and derivates).

You can just install the vanilla Silverblue and then rebase to Kionite, uBlue, Bazzite, and so on. And if you don't like it, just roll back/ re-rebase without any hazzle or risks. Your user data are separated from the system and don't need to get copied from your backup like usually.

What you might like:

• Immutable and hard to break. If something breaks (bad update or user fault), roll back. Works even better than Snapper (Tumbleweed) imo, which is pretty much the best BTRFS-implementation. You don't need to restore it, you just select the image and boot.
• Can be rebased (underlying system swapped out) to anything you want. Switch from KDE to Gnome because it now has a feature you missed? One command, a few minutes waiting time for the download, reboot, and you've got a clean "new" system with all your userdata and stuff unchanged!
• No reboot for updates required, they just install in the background and get applied when you boot up your PC the next time.
• Cutting edge, but stable.
• Doesn't only support Flatpak, but relies on it (at least that's recommended).
• Install any software you want with Distrobox. Arch, Debian, whatever. Comes pre-installed (uBlue at least) and is an integral part of your workflow if you use the terminal.
• Great KDE implementation.

A lot of the comments don't fit your criteria. Everyone is just recommending the distro they like. Which is fine, but they should at least say that.

I personally don't have a good answer either. Most my experience is in minimal distros that let you built out those components yourself. It may be worth considering that option (in which case, Arch is a natural next step), but you have to explicitly install wayland / flatpak / kde / etc to fit your criteria.

Wayland is more of a DE thing

Kubuntu with the ubiquity installer will install onto btrfs. Flatpack is easy to add.

Add in system76 scheduler and an up to date kernel like xanmod and youve got 90% of what gaming distros will do.

If you're using flatpak you don't have to worry that the host system has old mesa.

This sort of setup is probably trivial to do in arch as well.

To could to try to distrowatch.com to

Try Parrot OS, Home edition. Smooth, reliable, does everything well and super easy to add your favourite opensource software. It's flagged as a security distro, but it's actually a highly rated Distro without any of that

Can't help you. I use Garuda myself and it's my favorite distro right now.

Garuda was my first distro too, after it I switched to Endeavouros, I think that endeavouros or arch fill those requirements.