How to add a Button to send an MQTT command

Thanks, I already know and use node-red. From Grafana side, this Button Panel I see it supports GET and POST HTTP. I would try to install this MQTT panel geeks-r-us/mqtt-panel. But I don’t understand how to do it.
The problem is that I need to run Grafana on a server and then use mqtt since my device LAN is under NAT and not reachable from outside