From what I remember Nobara and Cachy (I guess Cathy was a typo?) don’t have Discovery and some home baked software managers that I didn’t like. Also, Nobara is too gamer oriented, and for games it works great since it’s created by Glorious Eggrol, the dev who created Proton GE. But for everyday use, not so much imho.
For now, I’m staying away from Arch based distros. I’m trying to explore the Debian/Ubuntu side first, since this is what I’m mostly familiar with. Also, some apps are available as .deb packages and installing them with Discover on Ubuntu was easy.
Things have also changed a bit since I decided to remove NVIDIA from the process. Perhaps this was the breakthrough that I needed 
I installed Kubuntu 25 (Wayland) on Intel using CPU graphics only (i5 12600K) last night and I can already see a big difference in stability. I have not had a single crash yet. I have an AMD RX6000 GPU coming in few days.
I tried OpenSUSE but I ran into a bizarre issue: none of the ISO writers for Linux was able to create a working boot USB disk. Rufus and Etcher on Windows didn’t work also. Turns out the only way is to either use OpenSUSE Image Writer (chicken and egg problem) or Universal USB Installer on Windows (duh…). Somewhat discouraging. I booted a VM directly from the ISO before without problems, but on actual hardware this was a worrisome hiccup. Then the setup was a bit weird. I also read some OpenSUSE reviews and opinions and I figured I will try to get Kubuntu working first. With Snap removed it’s a good distro, feels familiar and there is a lot of Ubuntu specific documentation and help on the web, more than any other distro.
I may also revise Fedora KDE, to see how the experience will be now, with NVIDIA removed from the picture. Fedora is the second base distro that I’m familiar with.
I’m leaving Arch and OpenSUSE for later. I have a feeling that either Kubuntu or Fedora should work for me now.
Some general Linux issues remain that are not directly related to KDE or even any particular distro, so they’re out of scope here.