One thing I noticed on Librem One mail on my phone is the “Quiet Time” in Notification Settings.
Oddly enough you only get to configure it for a certain range of hours. So if you want quiet time all day you have to tell it to start at a certain hour then tell it to quit a few minutes before. It leaves a few minutes of exposure to notifications at least once a day.
In other words there seems to be no way to tell to turn notifications off.
Just saying, it could be a new feature for next iteration.