Now that GPU Metal acceleration is possible in Big Sur with Parallels 16, that same performance is NECESSARY for macOS 10.14 and below. Many of us use Parallels for the purpose of 32 bit application support and need earlier versions of macOS to do real work. Please expand this support with such functionality or drivers. Now that we have seen efforts in the Hackintosh community to build native drivers we see that this kind of work is possible with virtual machines needing GPU acceleration. If you don't want to support such an effort, please open source it and invite the community to get involved.