there are a lot of good and usefull ones in the grafana community.
the basic k8s ones are awesome (and many of my personal dashboards are based of them), the Istio one is good.
I also remember vagually Redis and Ngnix has a good ones too.

but since they monitor a technical system, while I build products — I usually take charts, or get inspired from the comunity dashboards, and build a more buisness — centric one of my own.