Migrating users without username/password

I’m considering Auth0 for a project with thousands of already active users. I was trying to understand what’s available for the user migrations such as here: https://auth0.com/learn/migrate-user-database-auth0/

However, my users do not currently use a username and password. 100% of my authentication today is through SSO (either social, or enterprise saml). Is it at all possible for the automated on-the-fly migration to work without a username and password combo? I’m not finding many examples.

I am also keen to find out about this as a section of our users were created using Social and have no password.