Yea, seriously im so surprised that there are some major features that continue to be more or less ignored.... as the world we are set to assume things should work in a similar fashion. The board works fine in all mobile browsers but still lack the push notification. so all you can get is an email and only if you set the options right in the ocp.
Anyhew there are a few extensions out there a few have been more or less abondonded. but this one is recent.
however... NONE of them support Apple porducts. imho thats at least 50 percent of my people.... so why bother.
https://senky.github.io/pushnotifications/
I beleive you have to pay for this particular one.
There are also a few 3rd party APPs out there... but last i checked the best one didnt work.... wouldnt allow logins to a 3.3 board.
so yea.... not much