As suggested elsewhere, I think your requirements map quite well to Linux Mint. I prefer the Debian Edition but it has a shorter support window ( not LTS ).
If you want / need selinux then you may prefer the RHEL camp. Others have proposed Rocky. I would do Alma ( especially given your security focus ). Either way, the desktop software is going to be ancient and package selection limited. One solution is Flatpak. Another is distrobox.
An Alma desktop with applications coming from an Arch install via Distrobox would be the best of both worlds. The desktop and overall environment would be rock stable, secure, and boring. Yet the library of applications would be huge and, once installed, they would stay very up-to-date.”