Hey thanks for the Q: We will support other CI systems than GitHub Actions, but exact timeline of which and when is TBD.

With regards to cost, you can self-host GitHub Actions runners. Internally we use an autoscaling group of spot instances via k8s, which is much cheaper than GitHub-hosted runners. We actually didn't do it for the cost, we did it because we wanted a local cache to persist on machines during the day, for performance reasons. When cost is a factor, having an analytics system help you optimize your jobs is super important.