Anything involving paper is usually easy/cheap to get started with. Perler beads are also simple and don't take a lot of time or supplies if you keep it simple to pass the time. I think editing could be a cool hobby as well since it just requires a device. Making mixtapes and making cover art for said mixtapes /cd's.
All my hobbies are indoor hobbies lol. Except for analog photography which I suck at, bc my pictures never develop oof