That’s the thing. I don’t know lol. What do I do with the pub key?
Discussion
Basically this, as you already have seen.
As the other one mentioned, it's pretty much just a random ID you have. From a user's perspective it might seem like a phone number. You buy a random one once, then you share it with everyone to call you, except here they'd follow you rather than calling you & it's totally free. 👍