[usrusr]

> The important question would be if Github forks and pull requests are an open protocol or attached to the platform.

Attached to the platform, but open. You could do all the work on your feature branch somewhere else, say, your company's gitlab installation, then when it's done, push the branch into your github "fork" and and create a pull request there. I really don't know on which side of an openness line that would fall, you can easily define the line around it either way.