I have currently on RPI3 with snips. It uses its own broker and I bridged the home-assistant mqtt broker with the snips broker. For the bridging you might need to add a different prefix for each snips RPI so that you can differentiate which is which.
I haven’t been able to dive into snips yet but hope to this weekend.
Since I posted this, snips came out with a few updates. One of them should address this. There is now a way to have one central brain that would talk to HA. All the other snips around the house would be clients to the brain.