Software is always user-upgradable on Linux. Just install it somewhere in your home directory. GNU Stow [0] can be helpful as a very lightweight way to manage the packages.
(Of course, then you take on the responsibility of keeping up with patch releases yourself, which is why we use distros. But if it's just a small number of packages on top of a distro-managed base system, it's perhaps not so bad.)
I agree that compiling Python from source is surprisingly straight forward, but is that a serious question?
Have you ever worked in a place that uses Python? When someone says to you "hey it's not working" are you really going to say with a straight face "oh yes, you just need to compile Python from source". Come on, this is one of those obviously stupid situations that for some reason people feel the need to defend. It's not defensible.
You don't need to compile Node or Rust or Go or Deno from source to install the latest version.
Just run the miniforge install script if you want a very friction-free install. I'm not a big conda fan, but the "install in my home directory" use case is very well covered by miniforge.
https://github.com/conda-forge/miniforge/
Are you really going to support rhel8 as a platform for your project which uses specific python 3.12 rc3 features? Well there's always podman, I guess.
(Of course, then you take on the responsibility of keeping up with patch releases yourself, which is why we use distros. But if it's just a small number of packages on top of a distro-managed base system, it's perhaps not so bad.)
[0] https://www.gnu.org/software/stow/