I use a humidity sensor, motion sensor and a helper that shows the change over a period of time. If the humidity raises fast (+2%/5m) and goes over a certain amount (unique, depending on your room’s climate) the bathroom automation changes tracks to hold the light at 100%, turn the extractor fan on, and well, how you stop the automation depends on you. I let it stay on for 15 minutes before waiting for motion. Small tips: For me the humidity triggers the automation within 15s-1m of showering, which is okay for me. Motion sensors typically use IR to see movement. If the room is too steamy it might struggle to see you. Also, it cannot penetrate glass. It must have a line of sight to you.
The best alt I think would be mmwave presence sensors, but they’re pricy and require a wired connection.

I just signed myself with an ID app (Not the government one, fuck the state). The government has my data, not only because I have a passport, but because it’s a strict mandate that every living human is recorded, so they can tax our existence from our very first breath to our last (some folk are still capitalism-coded so I’ll specify that their rules, politics, taxes and frequent threats are very mentally taxing). So, given that they and at least a few Chinese-origin, potentially drop-shipping wholesalers have my legal alias and home address, I figure an ID verification company is the least of my worries.
The most we can do is choose when we comply.