I think tailscale supports exactly that? You give them your email address and they check the web finger endpoint of the domain for your configured SSO provider.

I think tailscale supports exactly that? You give them your email address and they check the web finger endpoint of the domain for your configured SSO provider. https://tailscale.com/kb/1240/sso-custom-oidc https://tailscale.com/kb/1240/sso-custom-oidc