Nothing. Everyone is using nothing for push notifications.

what do you mean by push notifications?

I use this: https://play.google.com/store/apps/details?id=de.cyberdream.androidtv.notifications.google&hl=en

Which is not ideal, you need an Android phone on your wifi and this basically mirrors that. It's unreliable for me (oops, forgot to switch my phone to wifi, etc), but it's currently the best solution I've found so far.