Chatting with nostr:npub1f49twdlzlw667r74jz6t06xxlemd8gp2j7g77l76easpl8jsltvqvlzpez reminded me of a project that some students in a communications club I was part of during college.

They created a packet tracker (I assume this wasn't novel although they received grant money from some military contractors, which is normal for my school). They were able to track anything that emitted 802.11 packets of any kind, which included device specific information down to 1 meter, over about 1 mile with a single antenna, a cheap SDR and GNU radio. As long as most smart phones are on, they emit traceable 802.11 packets. Something to consider. You just need a large enough antenna network to change that area. I wouldn't be surprised if Ring doorbells and Google homes already do this.