In my area people are selling off their rental properties these days, as the return isn’t worth it any more. I’m sure there are markets where you can still earn a lot that way, but if you’re not interested in being a landlord, don’t become one. If you want a quiet life, keep investing in a diversified portfolio. It’s ok to have other values and goals.
Lokal volunteer run radio, if you have something like that in your area. Find out when they recruit or send them a mail. There are several in my area, and they are very social, perfect wether you want to talk, code, write, do audio or something else. You can often start from zero there, or find a way to use something you already know.
A sort of hunger bar. It would be useful in so many situations.
I wouldn’t do it because of the fire hazard. Better to use hardware that is meant to run 24/7 plugged in.