When you’re not home it becomes part of the alarm system. When you are home it can turn on the lights or heating (or extractor fan in the bathroom) and you can aggregate it with other sensors to measure occupancy to turn those things off again. If you use Home Assistant (or something like it) you can use it to go anything that can be inferred from a door being used.

Don’t listen to him. Sure it may take a few hours a day over the course of a month or so to get right, but with the time you’ll save from all that automation you’ll break even in a few hundred years - and then it’s all gravy!

You’ll pay through the nose, but look at digital signage panels. They are bristling with I/O, configurable to the nth degree, wonderfully over-engineered and utterly free from bloat.

It’s called “eliminating competition”.