As someone who have tried upstreaming a patch for Emacs on macOS (to add a feature that already existed on Linux), I can bitterly say that at least some of the maintainers do have a disdain for non-free OSes and that it makes it contributing patches for macOS as miserable as possible.

The patch was adding xwidget webkit support for macOS Cocoa[0], which I iterated for the next few months[1], only to side-rail into a discussion on macOS/GCC and GNUStep support policy[2], and I fizzled out.

That was abt 5 years ago, and I’ve never touched on the Emacs codebase since.

[0]: https://lists.gnu.org/archive/html/emacs-devel/2019-05/msg00...

[1]: https://lists.gnu.org/archive/html/emacs-devel/2019-07/threa...

[2]: https://lists.gnu.org/archive/html/emacs-devel/2019-08/msg00...