If you really must use it, GPU passthrough has been achieved on Linux by some users and on Windows by others, but compromises your security. However, this might be worth it depending on your threat model. If I were you, I’d stick all 3D applications on a GPU-equipped offline machine and run Qubes somewhere else, having it handle all other tasks (including downloading, say, assets for Blender). I’d ferry information to and from the PCs using USB (or SSH if you can secure that).
(Note I am not an expert on Qubes, security, or anything else, so take whatever I write with a grain of salt)