Restricted or Conditional Access for Firebase Links

Hi - I am creating a loan tracking app, and one part of it is allowing users to upload tax docs. The concern is where the uploaded file is saved, if it can be deleted, and if the Firebase link is secure. Does anyone know if Firebase files can be deleted yet? From what I have gathered in other posts, it doesn’t look like. Does anyone know if a Firebase link can be restricted to use by a certain email address? Or can a Firebase link be given conditional access? Thank you!

They are secure in the sense that they have a token and can’t easily be guessed, but as far as i know, the link is public.