Would anyone be interested in using Docker for this? It should be possible to make the same Docker image work on Linux, Windows and Mac. I could probably make it so it looks a bit like this:
git clone docker-build-repo-URL
docker build
docker run some-magiclantern-repo-URL 200D
And it pulls the magiclantern repo you're interested in, builds for 200D and drops the files outside of docker, ready to put on your card. Installing docker is left as an exercise for the reader but should be pretty easy. As a bonus this would guarantee that everybody can automatically use the same versions of compiler, make, etc, which is nice for the devs.
A little off topic for this thread, so please message me if this sounds like a good idea, and I'll try and get it working.