What to do with old phones?

I found a few old phones from my family. II cleaned them, installed LineageOS and rooted most of them. On one I installed postmarketOS, one is still stock Android and one is lets say bricked (after installing lineagesos it stay on boot logo for ever, before that I installed lineageos and nethunter on it). One one disk encryption doesnt work for some reason.

Phones (all samsung galaxy):

• S4
• A5
• A5 (bricked)
• A5 (postmarketOS)
• J3
• J4+ (no encryption)
• A31 (stock)

What can I do with them? Something like Monero node or Tor relay, but I'm already running that on old pc. For something that needs speed I have rpis (like a website). Camera security system? Tracking device?

Is it possible to run (and autorun) cli apps and/or services that can access interent, bluetooth, gps, sensors, camera, files, etc. just like on linux? I'm a programmer and I don't like making normal android apps for a simple project.