You couldn't pay me a billion dollars to use Okta.
OIDC is not scary, and advanced central authorization features (beyond group memberships) are a big ole YAGNI / complexity trap.
This isn't email.
Yes, you need someone to wear the IAM admin hat. But once you get it configured and running it requires 0.1 FTE or less (likely identical to whatever your Okta admin would be). Not worth 6+ figures a year and exposure to Okta breach risk.
Yes, creating a SAML integration is easy, but that's only one piece of the puzzle.