I dont know if its the app or if its the way Apple devices handle Bluetooth, but when I wake my Mac and want to use knock, which is really the only time you would need to input the password, it mostly doesnt connect or it takes 5 minutes, making the whole thing knock idea an unnecessary complication. Its a nice trick, but unfortunately it was left at that. I hope this will change in the near future...
Thr Monk about Knock – unlock your Mac without a password using your iPhone and Apple Watch, v1.1