It's also incredibly expensive per-connection if you use something like WorkOS to handle SSO/SAML. The only way to make the financials work is to only offer it on enterprise tiers.
On the note of oss and sso that works well for b2b. Zitadel can be tool to get rid of the plumbing work that you encounter with all the permutations one can have with the different customer requirements.
Disclaimer: I am a co-founder