But SSO support does feel like an enterprise feature that people typically pay for.
I can’t think of any other feature gate that would work as well for software such as this. Though it typically is the largest hinderance to SSO adoption.
I think security and therefore SSO should not be an optional feature. See https://sso.tax/
Obviously big companies will pay for SSO because they must have SSO. At my scale I skip products that are overpricing SSO or I put them behind a oauth2-proxy when I can.