You can always use pyenv to install any Python on any mainstream Linux. I only use pyenv Python to develop on any laptop or any server. My dev laptop is still Ubuntu 22.04 and I have any Python from 2.7 to 3.14 .
Incompatibility with Python version in current LTS Ubuntu sounds like an issue to me.
FWIW I used to be fine with just dealing with system Python, like you, but recent tools like uv make it so easy and convenient to isolate interpreters and dependencies per project that I'm just not going back.
Yes, that's pretty typical. I think there's a general assumption if you're using older python you'll probably stick to Django LTS 5.2 from this April which still supports Python 3.10.
https://github.com/pyenv/pyenv
Simple Python version management