I would love this! I recently made a change in my availability (COVID, right?) and I keep forgetting as I'm viewing my calendar while in a session with a client, offering them a time that I can't actually give anymore!
My hours change regularly. I keep having to look up my hours (make sure I am remembering the latest change) or get denied making an appointment and have to go back and tick the after hours override. I wish the hours I am unavailable were grayed out on my appointments schedule.