poVoq that is exactly the package that kyrne uses on his extension.
poVoq Anyways would be cool if anyone here could share their experience with helf-hosting a pusher-like service for use with Flarum.
For Blomstra I decided to create a custom implementation (blomstra/realtime) which is much more thinned down to the basic needs of a Flarum forum. We haven't decided yet on how to publish this (most likely premium or paid support). But this shows that "rolling your own" is certainly possible.
We are successfully using our realtime extension on our client websites already, it seems to scale perfectly.