Muzzle is described as 'A mac app to silence embarrassing notifications while screen sharing' and is an app in the remote work & education category. There are 2 alternatives to Muzzle for Mac and Android. The best Muzzle alternative is NoPopping, which is free.
Turn banners off in System Settings and notifications still arrive in Notification Center. Nonja reads them from there and builds a list in your menu bar, grouped by the app that sent them. Nothing appears over your work.