I have one where I put a door/window sensor on a window and anytime that window is opened it turns off the HVAC, then when closed, turns it back on.

I tried once to setup a notification to open the windows if the weather was nice, but I’d never gotten to work quite like I wanted, and so I turned it off.

https://a.co/d/2Il1Ors

looks like these are the rechargable version.

You can buy rechargable coin batteries.

One big VM dedicated to BOINC project of your choosing.