There are powerbanks with solar cells and even in a day which is not sunny, those things will slowly charge the powerbank if you leave it under natural light for a few hours (from what I read you get roughly half the rated power from solar cells in a cloudy day).

Yeah it’s a safe in my office and I often go back to it for small projects so the stuff mostly works and in good contion just instead of a plastic box its a big ol’ iron safe as a lazy precaution and decoration.

One note on safe as a Faraday though is that it has to be a full metal without any rubber seals as any gaps will leak so an old safe is often perfect for this. It also needs to be closed so you want to disable the lock as it’s pita to use otherwise and you’ll never touch the devices there.

As you pointed out key to sustainable tech is that it has to be used from time to time as if you just put it away in a basement or something it might as well be as good as dead.