It just hit me that when we have signups from invites in akkounts, we could automatically store roster information for the new user and the person who invited them (i.e. add them to each other’s authorized contacts). This way, there should be no friction in terms of OMEMO key exchange, and they would already see the other person when they’re online in most clients.
API endpoint for implementation: Administration API reference | ejabberd Docs
Just opened PRs for akkounts and chef, which add this feature: