I currently run all my lights etc via NodeRed on a Pi3 - could I set up Home Assistant on a Pi5 and run all the Node Red, MQTT, Grafana and InfluxDB things on hat instead? and is it fairly easy to set up and transfer acress
The way NR ties into HA is through the HA websocket nodes. You can connect to a stand alone instance, if you wanted to keep the pi 3 with NR.
If you wanted it all on the pi5 then you would export all your flows and import them to into the new instance. This does not copy over context data stores though. If you do use them and need to preserve that data, I’m not sure if that can be done.