To get the purple verified Nostr tick mark on your profile check out
For a few Sats the you can register on their site with your Nostr handle and get verified
Nostr Plebs | Get a Nostr Address (NIP-05)
Nostr Plebs is an easy way of getting a NIP-05 identifier/Nostr Address and other Nostr services, made by Bitcoiners, for Bitcoiners.