Is this meant as a Proton Notes equivalent ?

I found this as well on f-droid,Tunerly but I don’t know if that is indeed what you meant.

We could wait for the implementation from the GrapheneOS team ! I’m pretty sure that they would implement it in a way that would be safe for the user.

You could try Session. It makes a session ID like this . This can be used to contact people or for people to contact you. I’ve used it to talk to my SO a bunch of times.