This may sound surprising, but my understanding is as follows: the moment you alter Grafana in any way, you may no longer us the Grafana name and logo anywhere. See Is it possible to use unmodified Grafana in our commercial cloud platform? which I believe is still correct. Also Trademark Policy | Grafana Labs.
So you should certainly be able to white label in the way you describe (subject to AGPL license requirements, assuming you’re using v8), but if you do that you’re no longer allowed to call the service “Grafana”.