There are already a few 3rd party projects in the works such as the Nebula driver that provides hardware 3D acceleration on NVIDIA Turing architecture and above cards, based on the open source driver. More about that on this thread.
I also see someone is working on hardware 3D acceleration for the AMD cards they have access to in this thread.
There has been a lot more work done on improving the situation recently as the above examples show, even if they are not an official part of the Haiku project.
As you are aware, this is a project of mainly volunteers with limited time and resources. If someone is willing to contribute in a way that speeds up the development pace in this area, I’m sure it would certainly be most welcome.