Using #Amethyst for some time but I never manage to make the notifications work properly. I get one from time to time, mostly for a zap, but nothing for a new private message, reply or mention. Of course if I open the app I see all of then in the relevant tab.
I tried the Foss version with UnifierPush from Nextcloud and even the Play version with Google Play, but 95% of the time I don't get a popup notification. I'm on GrapheneOS by the way.