first version

works well for us - limited to xc16 though.

The biggest problem is that it takes 10minutes to build the docker image and github does not seem to cache it between invocations (it will be cached for the duration of the build but it would be nice to not rebuild the image every time).

It seems they might fix this in mid November. Until then I would recommend building the image, pushing it to docker hub and using this. Don't make it public because you would be distributing mplab/xc16 which is not authorized by the license AFAIU.