[Razengan]

What if people could choose to donate their devices' computing power in return for some Netcoin or whatever?

[immibis]

You can do this. Several services pay you real money (not much) in exchange for letting AI scrapers use you as a proxy. It's completely legal (AFAIK).

[Razengan]

Not my internet connection, just the CPU/GPU/RAM, just when it's charging, and so on

Or those could be separate options