I've got a 2015 MacBook Pro running Monterey which I can code on. It's offline (no DNS entries) but I can AirDrop[1] stuff to it. I use Dash[2] for offline documentation and Sublime Text[3] for editing.
It's really just an experiment to see how little (software, hardware and internet) I can get away with. We are moving next year and I may not have space for the large desk and monitor I have now.
[1] https://en.wikipedia.org/wiki/AirDrop
[2] https://kapeli.com/dash
[3] https://www.sublimetext.com