Thank you very much for the response.
I tried following it but right at the end, pyenv is not giving me the confirmation it has installed Python but rather it is rebooting with no error message. Running ‘python --version’ still shows the 3.9.x release. The same seems to happen when I install (altinstall) Python 3.11.x manually, which perhaps is not what it should do but I’ve never installed Python before. Are there any logs I could look at to see why it’s failing? This is a vanilla Raspbian Bullseye install and then immediately installing the dependencies and Python so I can’t understand why it would just fail…