I cannot speak to FC since I've never run it. Did you try installing Quartz X11 first and running 0.19 against that? It might pick up the Quartz X11 OpenGL drivers that way and it might work better (if that's what the FC developers target). It will depend on the features used by FC and those supported by the lib though.
There are technologies in development that intend to bring back good OpenGL support to macOS. MoltenVK is already quite good at implementing Vulkan on top of Metal/Metal2 and the rust-based gfx-portability project aims for the same thing. After that there's another project called Zink: https://www.collabora.com/news-and-blog/blog/2018/10/31/introducing-zink-opengl-implementation-vulkan/
which then implements OpenGL on top of Vulkan. Yes, this involves a few layers but in theory it would work to some extent! It would involve some translation layers but they are quite slim.
At the end of the day, Apple made a call here which means getting OpenGL to work well on Apple OSes in future requires someone to do a good amount of work (thankfully mostly already done or in progress!).
But OpenGL is such a bad graphics API anyway that the best thing would be for projects to switch to Vulkan at this point. I doubt that's easy for FreeCad to do though at this stage, but that will depend on how cleanly they interface with the OpenGL API in their code.
FWIW, I do have an interest in getting all this to work within conda on defaults (including OpenGL for what I'd like to call 'legacy OpenGL' apps at this point). I've started some work on adding both MoltenVK and gfx-portability packages. If you are interested the please let me know.