Hi there,
I did the same thing a while ago, while we started with a JSON API written in Lumen but also we wanted to have real time chat . All those solutions in PHP for real time communications where not so good and we finally choosed Socket.IO.
For that, we created a small instance of nodeJS with express framework and added socket.io on both Client(Browser) and Server (NodeJs)
Real time communication was in place, but we also wanted to save messages into Database and since Lumen is already linked to our MySQL instance, we had to find a way of communication bidirectional between NodeJs and Lumen.
Redis can do that. It's really fast and light because it's just a key value cache system.
We implemented also a publish subscriber pattern to immediate react when some value is changed in Redis for specific key. So implementing both a subscriber and a published on both Lumen/Laravel and NodeJS will bring you the benefit of pushing data from/to Lumen and NodeJs.
Please do more research on Redis.
Thanks.