I'm wondering if a distro like the one I'm looking for even exists:
- simple as in KISS and vanilla. This excludes Debian where the package manager is too complex and packages deviate from upstream too much, as well as OpenSUSE, where systems administration relies on GUI tools too much and the package manager is even more complex.
- fixed release (excludes everything Arch-based)
So from the major distros, only Fedora is left as an option, where I really don't know enough about it. Is it possible to do a minimal install of it? Is it built around a GUI app store? Does it rely on Flatpak like Ubuntu does with Snap?
Or are there other distros out there that I'm not aware of? Basically everything from the past 5 years I have no experience with. I've heard good things about NixOS, but it sounds weird as a daily driver.
You complained about reliance on GUI tools, so you're going to have to explain how that isn't easy to use if folk are to help you. What is the issue with that for you?
Most stuff on opensuse, you can also do on command line. Having a GUI to help people who like a GUI doesn't mean people who like command line aren't facilitated.