I have no other good examples for SSO than Grafana.
But something I would love to see more for logins are Application Tokens. We use Cloudflare Access for Team related logins, which will send such a token in the header, so the application can use it to authorize a user and by which group a user is in it can enable/disable features
https://developers.cloudflare.com/cloudflare-one/identity/au...
This solved our needs for multiple sign in options, as all is now managed through Cloudflare access, but this is obviously not a solution for everyone