i did hear about some shower drains that reuse the heat like this one: https://www.youtube.com/watch?v=s5bJ61fCA2E

Sortof i guess https://mailcow.email/

Yup, droidcam obs - you'll need obs with the plugin, but its a one time fee

Its pretty nice in my opinion, have been using it the last 2 years without a flaw

a short research shows, this is the cofounder of keepsafe, so i guess they most likely got the data from their customers