So... I'm going to be that person, yes, you already where it's going : how about no tech? How about a box, wooden, plastic, whatever, where you put the keys inside? Always.
I know it doesn't sound fancy, and as somebody who is turning the light on and off above his head with a keyboard shortcut I genuinely understand the challenge, but... in terms of privacy it is hard to beat.
Now... assuming you have HomeAssistant (as I do) and still really want to still do that and are ready to setup an "infrastructure" (to be able to do the zoning) this https://www.linuxmo.com/how-to-create-a-bluetooth-tracker-with-home-assistant-and-esphome/ looks like a proper solution that does work and is fine in terms of privacy. It does look like a lot of work to be honest, and it would only work in your house (or office if it's yours so you can do the zoning there too) rather than going through the network of mobile devices that Apple and Android do... but it would be a start.