Yes, see for example https://www.forbes.com/sites/jasonevangelho/2019/09/19/fine-wine-an-interview-with-codeweavers-about-valve-windows-and-the-future-of-gaming

Yes, see for example https://www.forbes.com/sites/jasonevangelho/2019/09/19/fine-wine-an-interview-with-codeweavers-about-valve-windows-and-the-future-of-gaming-on-linux/ https://www.forbes.com/sites/jasonevangelho/2019/09/19/fine-.... CrossOver and Proton are rather independent as codebases, except they're both constantly rebased on Wine. Of course patches can flow in both directions (and from either to vanilla Wine, which is the best), but AFAIK none is systematically based on the other.