IRM with alerting from Grafana OSS

Has anyone set up Grafana Cloud with IRM with alerting from Grafana OSS? I’m quite happy with the OSS TIG stack we have and was told by sales that the link is possible. But as I’m still on the free tier of Grafana Cloud (IRM) I’m being pointed to the forum for help.

I don’t mind paying for stuff, but want to know what will and what won’t work. I’ve looked at OnCall as well but haven’t built the backend yet, so still need to assess that. It wouldn’t surprise me if OnCall is the element that would tie the two together.