Joe Kissell, in an email today announcing Glen Fleishman’s new book, Take Control of Focus:

Glenn Fleishman is back with a brand-new book that helps Apple users manage notifications and the many varieties of audible, visual, and tactile alerts across their devices. Take Control of Focus shows you how to use Apple’s Focus feature to impose order on the many beeps, buzzes, and “Pay Attention to Me Now!” doohickeys we encounter all day long.

On a related note, an Applescript I found to clear notifications on the Mac:

tell application "System Events"
    tell process "NotificationCenter"
        try
            perform (actions of UI elements of UI element 1 of scroll area 1 of group 1 of group 1 of window "Notification Center" whose name starts with "Name:Close" or name starts with "Name:Clear All")
        end try
    end tell
end tell

You can run this as an Applescript, of course, or make a Shortcut, Keyboard Maestro macro, or ExtraBar action.