Cat7 and LC fiber. If all the runs are under 30m you can use cat8. I wouldn’t bother with 5e on a new build.

Probably a k3s cluster. The bigger constraint will be memory.

Definitely interested in the boards and backplanes. Any plans for expansion (i.e. ribbon cable connected PCIe)?

Clearly I misread the original post. A remote relay would be the simplest solution, assuming there are no outlets down-wire from the one you’re looking to control. Otherwise you’re likely looking at an extension cord to another outlet or doing some home wiring.

Cheapest option - look into wireless meat probes. You can put the probe in the attic and the unit in conditioned space.

It’s a $50 door stop. Westmere is now 13 years old.

There are a few options for local NVRs such as Blue Iris or Frigate. Both can do facial/object recognition. They’ll work with any camera that supports direct access.