I am using Fedora Kinoite and it has been incredibly stable. I like that I can always rollback to a previous state if an update breaks something. This was a huge issue for me a couple of years ago and I stopped using Linux for quite some time because of that. I haven’t had to roll back anything yet but without that feature I wouldn’t even consider making a Linux distro my daily driver. Installing software is for the most part pretty easy if you are happy using flatpak applications and toolbox. I like that all the packages that I need for my work or for messing around stay in the toolbox container and won’t affect the stability of my system. The only thing I find a bit annoying is that you have to reboot to apply updates. For me, going back to a ‘mutable’ distro is out of the question.
The part about changing the login screen seems to be not entirely true. There is also this tool that claims to be able to generate rpm from sddm themes that you then can layer onto your system image. Take this with a grain of salt though, as I haven’t tried either method because I honestly don’t care how my login screen looks.