You could keep the YAML format and extend it, and still write compose files as pure Python.
- locally install jekyll
- write my .md files
- run jekyll locally to see how my site looks like
- commit .md and .html files
- let github pages know what you are pushing the static files yourself
The issues with using an older shuffle is that replacing the batteries on ANY of them is a massive chore, and none of them have bluetooth, which means you'd be back to dangling wires, which (imo) sucks when running. I believe the later generation nanos supported BT, though, so they might be a cheap candidate for a "music while running" solution.
Now that I think about it, I wonder if Apple has ever explored turning the AirPods case into a mini iPod. I guess their iPod days are over but it'd be a really neat little device.
Edit: Apparently this exists! https://bemighty.com/products/mighty-vibe