Can I add users outside of my tenant to my Power Bi Premium capacity workspace?

I want to share Power Bi Report published in a Premium Capacity workspace with multiple clients. Using RLS, the data model will filter according to USERPRINCIPALNAME() so clients only see their own data. The users in client's tenant have Free Accounts and no Pro licenses.

1) Can I add users outside of my tenant to this Premium Capacity workspace in my tenant?
2) If yes/no, would the external user still need a Power BI Pro license to view and interact with the report?