Grafana OSS does support SSO out of the box, at least OIDC (which is a technically superior standard to SAML w.r.t. security).
The Enterprise edition seems to focus a lot on meta-information about grafana itself: the most frequently accessed dashboard, who is viewing the current dashboard etc.
Theres also group-sync, I guess, which is useful, but honestly the selling point of enterprise is the support I think.
In fact, I might buy enterprise following this, the fact that so much is in the base product gives me the warm fuzzies.
Given a lot of their software is OSS or OSS based there's a probable chance non-OSS is runnable and usable outside the company
The product is mostly "standalone" in that it doesn't require integrations with 3rd parties unlike, say, banking software