Just a quick post, I have a Factory Unlocked S9, which I keep updated to the last baseband/security update. This phone should still fall within the Samsung monthly security update plan. The current baseband was released on Sep 21, 2020. Today, it is 53 days old.
Nine Plus Weeks - the Samsung Pro answer "Shut up and wait until you are deemed worthy." The US locked phones have gotten 3 updates since the Unlocked version was last updated. I know just for future buyers looking at Samsung for a phone and expecting it to be supported.