[nolok]

About 1, unless you have a dev team and dedicated time to make compatibility layers, you're more or less limited to whatever application and saas supports your sso of choice though, correct ?

[cj]

No, SAML is the standard these days and it’s supported nearly everywhere (where it matters). No vendor lock-in.

Although I’m not sure why you’d go with a 3rd party idp rather than just using Google Workspace (or Microsoft equivalent).