Today I discovered ' Disourse '
from Google for Android.
With this app installed you are kept up to date
about forum content changes at a glance.
I give it a spin right now,
my first impression is OK so far.
My second impression after 4 hours of use is good,
Notifications of new posts and messages are displayed reliably
and you get in the notification field a hint as well as an acoustic signal.
Good, but more relevant for moderators