Not a dev, so I don't know if it's feasible or easy to do but another idea I had is making a general rss feed that contains all new posts for that board and each rss item has to include information on the thread that the post belongs to, so that everyone can setup rules in their reader to filter for the threads and egirls they are interested in.
I use a telegram rss feed bot so I receive notifs directly on my phone. It would be pretty handy something like that.