Pushover support. Notifo is basically the same thing, but Pushover supports all platforms while Notifo has been "in development" with their other platforms for the last several months.
There are other alternatives listed in their farewell message. Since
they're no longer in service the 'notifo' field in profiles on HN and
the arclanguage.org form can (should?) be removed.
Personally, I hate notifications, but of course, tastes vary, and some
people really do love getting an endless stream of notifications. The
trouble, or course, is which service to integrate, and how triggering
should be done. It's not as simple as it might seem at first glance.
Worse yet, HN (actually news.arc) runs as a single thread on a single
system, so the performance impact of adding notifications might make
them infeasible.
https://pushover.net/