Honestly, without Vulkan support, and with only OpenGL 3.3 available.. my use case for Parallels is a increasingly diminished.
I'm a game developer, I mostly focus on OpenGL and increasingly Vulkan. Having the ability to target these frameworks via Parallels is of great benefit to me, as a developer.
I may yet explore DX11 (which is supported), and perhaps one day DX12 might become an option.. but the world is bigger than Direct-X
I may have to ask for a refund on my Pro subscription until Parallels can offer up a roadmap that meets my objectives.. until then, I'll just keep using a Remote Desktop to a real PC.