Status Update
Gog.com approved the Linux version of Boxedwine for the game, The Voodoo Kid. Now that game is available on Windows, Mac and Linux on Gog and Steam. All 3 builds are using the x64 multi-threaded version of the CPU emulator. This is a good start, but I still have some work to do on the Mac build before I can say all 3 platforms support 3D graphics.
As for the Mac build, I had 2 choices to fix the GL frame buffer issue. I could port over what Wine did in their mac driver, or I could try Vulkan. Since Mac deprecated OpenGL I decided spend my effort on Vulkan. Marshaling Vulkan from 32-bit emulated land to 64-bit host is a bit more effort than I would have thought. A lot of Vulkan types have different sizes between 32-bit and 64-bit. Also Vulkan uses a lot of structures and in those structures they have pointers to other structures, so all of the pointers need to be marshaled too. And on top of that, Wine 6 is the first version of Wine to include Direct3D to Vulkan translation, so I had to get Wine 6 to work with Boxedwine. That ended up being a bigger issue than I would have thought too. So progress has been slow but it is moving forward. Currently all the boiler plate code for the marshaling is done, Wine 6 file system is built for Boxedwine and it loads Vulkan with the first couple of calls successfully running on my NVidia GPU.
Of course, even if I finish the Vulkan work, there is no guarantee it will work well enough on Mac since Mac doesn't support Vulkan, I would have to use MoltenVK to translate Vulkan to Molten. And from what I understand that isn't perfect yet.