"Get a public key, safely, starting just with someone's social media username(s).
The goal is a simple way to look up and trust keys, based on known public identities."

Note that keybase has been bought by Zoom, which is not trusted by some people. See https://alexschroeder.ch/wiki/2020-05-08_Replacing_Keybase and https://idiomdrottning.org/pgp for an alternative using free software.