I’ve used an old, out-of-support phone as a permanently plugged-in homeassistant control panel. Not quite self-hosting as in phone-server, but a fun easy project and a great way to keep an old device in use.

Can you give us the full output of the following commands?

ip addr

sysctl net.ipv6.conf.all.disable_ipv6

I have a playlist of the allegro movements from a bunch of baroque violin and harpsichord corcertos that is really nice to do intense head-down work to. Mostly Bach.
Baroque for the structure - feels mathematical and easy to predict and follow, making it easy to listen to while focusing on something else. The allegro movements for the pace - upbeat and invigorating. And a concerto has a great balance between large-scale blended orchestral sound and the melody of a lead instrument which also lends itself to supporting your focus on something else from the background.