I don't mean to say your suggestion isn't worth it because I do think this would be nice, but have you tried pressing tab, pressing the alarm keybind, and then pressing tab again really quick?
Also one thing that you could try is to open up Blockland, tab out of it, and (if you are running windows, I know you can do this), adjust the volume for the application (output) down, therefore quieting that application only. Iirc it should persist so every time you open Blockland it will stay at that level.