The whole idea is a privacy minefield, so it would have to be very carefully designed and implemented, of course making it opt-in. But still, should we even pursue this idea?
So that, for example, even if I met someone just briefly, they can still later see the contact information that I am willing to provide.
Wouldn’t that make it much easier to connect with people who live close to you?
Are there any relevant projects or ideas that already exist?
Yes there is, it’s called a business card. It’s opt in, has all your relevant information, and best bit, no phones or proprietary software required.