Zoho being the IdP for OAUTH of our customers

Zoho being the IdP for OAUTH of our customers

Hi Zoho,

please guide me in the right direction if I'm misunderstanding things...

We are a small company, with about 20 users currently using Zoho CRM and books and other apps. As far as I know, CRM keeps a database of our customers, with name, email, address (but no password yet?).

We also have a customer-database in our homepage (wordpress (wp_users: name, email, passwordhash)), and customers need to login to view/download some things.

I'd like to unify these databases, and like for wordpress to use oauth (or maybe saml?) to authenticate against the zoho-database. Of course, I don't just want our 20 employees to authenticate, but also want our ~500 customers to authenticate against their records in zoho CRM.

1) Can this be done?
2) Using zoho vault or any other application? Who would be the Identity Provider (IdP)?
3) Would we need to sign up every customer like a normal employee of our company, paying per-customer? That would be a dealbreaker, of course.

Thanks for listening!
Ben