> I can tell you that the HD 5770 doesn't work for either MorphOS or MacOS.

While there's a possibility that it works or will work for MorphOS, it's technically impossible it works for Mac OS. So at least this part of your experience is fully expected.

> Does anyone know if it will be supported with the bounty for drivers?

The TinyGL update project also covers the GPU of the HD5770, but so does the current 2D driver...