Grafana Enterprise source code / Adding annotations as viewer

(not sure in which category to post this question)

Small question: Is the source code for the Grafana Enterprise features publically available (on github)? Or does Grafana Labs keep this offline to protect their incomes?

I am in high need to be able to let viewers create annotations, as quite some others: Annotation role · Issue #9991 · grafana/grafana · GitHub. Since Grafana Labs seems to ignore the demand for such (simple) functionality, I was thinking maybe it is possible to port (a part of ) Grafana Role-based access control (RBAC) | Grafana documentation to the open source version and build it myself, just with the purpose to be able to let viewers create annotations. Within the non-profit research environment I’m developing a tool for that uses grafana, there is simply no budget for an enterprise subscription to only make use of the role-based access control to let viewers add annotations.