How I finally solved this is I got a Mac Mini from cloud, I could with a lots of trouble finally start docker in it (needed a desktop to click some icons) and test my code. This meant statically linking OpenSSL instead, which is not the greatest from a security point of view.
All of this took six months, and it was really hard to get Mac users to commit anything. It was ridiculously annoying to write and test without buying an Apple computer.
After this experience I just don't want to support any of their products anymore. Too much time wasted.
There are absolutely OSS maintainers who wouldn't mind patching things for macOS... if they could figure out the expected behavior/etc. I've fixed things for projects that I only know about from plumbing around in AppKit for a few years now.
There is lots of cross-platform software, which works on Linux, Windows and even BSDs; you can't expect (or feel entitled for) open source maintainers to then also go ahead and buy expensive Apple hardware just to support their idiosyncratic almost-BSD-but-not-really-UNIX OS.