I noticed in the Drone 1.x roadmap that various runtimes are being developed/explored. That’s great to hear!
I would like to suggest another runtime. Podman is a container utility with a similar command line interface as Docker. It’s primary advantage is it creates containers as child processes of itself, rather than asking a daemon to do it. It also has excellent support for rootless containers. It can be integrated directly into golang code by using github.com/containers/libpod.
Dan Walsh and Mrunal Patel gave a talk at last year’s Red Hat Summit about podman/libpod and other related tools, I encourage you to take look! The whole talk is good, but if you’re short on time the podman-specific information is from 35:38 to 38:47.