Fedora Kinoite. I like KDE, atomic distros and the fact that Fedora is the only (at the least that I know of) distro that has proper SELinux implementation.
I also play games on this system, so having newer kernel and Mesa versions also help.
Use Aegis, which is also available on F-Droid.
UFW, by default, blocks all incoming requests. This means that SSH (port 22) is blocked already. Then, if you need to, whitelist (ALLOW) ports that you want to expose to the network. For example, I have ports 1714-1764 whitelisted for KDE Connect and everything else is blocked.
I suspect you have installed either Lutris or Steam through flatpak.
Try installing both using the same method or install MangoHud both as a flatpak and a system package.
Also, I recommend enabling MangoHud with 'MANGOHUD=1 %command%' instead.
This video is almost three months old, why post now?
It doesn't scale properly on my HiDPI laptop display, which I use at 200% scale (Plasma 6, Wayland). Some things are too big and others too small. Hopefully GIMP 3 will bring good scaling support with GTK 3. Still, I love GIMP and will continue to use it over any alternatives.