This is pretty neat, for anyone that uses github actions (The testing servers in github). It will let you test your github workflows locally (although I am not sure what kind of environment is required).
It might be useful if you were editing the v1docs workflows, to make sure they were still working, or building all of the marlinbuilder builds, especially if you were changing those workflows.
Probably not useful to most people, but a few people might find it very useful.