Collect, validate and store email address for federated identities without email

If i understand it correctly Auth0 does not have a built in way at signup to ask the user to enter their email, validate and store it for a federated login where email is not part. In my case an ‘Enterprise Connections OIDC’.

Is this correct? What would be the best way to achieve this? Redirect to a self hosted web page/form and then do the validation part in a Auth0 flow somehow? Where could the email address then be stored? In app or user metadata?

Thanks for any ideas.