I'm in a real build or buy struggle. GCP identity platform would serve almost all our needs.

Basically I want to build usermanagement on my own (including rbac and groups) and ONLY want to solve Login and tokens with the below requirements. I know quite a bit about jwt and authentication in general. The question I'm asking my self is just of its better to build a solution on my own or to use one existing.

Is there any alternative which supports the following:

• multi tenancy (at scale >10k tenants)
• MFA
• social login
• SSO with oidc and saml
• and of course persistence (using refresh tokens)

Are there any tipps for self building? Are there any alternatives? Any direction is greatly appreciated