If I were you, I’d look into something like the HP Reverb G2 that has inside-out tracking (no external cameras or lighthouses). The immersion you get with VR is way beyond anything you can get from a screen.
My full setup a Vive Pro 2 with a VKB HOSAS setup and a YawVR 2, and it feels spectacular, though getting interdicted the first time almost made me piss myself.
I have a similar build for similar reasons. It works great, though I use Windows, so no driver issues (VR introduces too much jank with Linux). Notes below.
CUDA is essential. Definitely the right call paying the Nvidia tax.
My Gigabyte 4090 works for LLM stuff without a second card, and has no coil whine I can hear. I use Alpaca 4-bit entirely in VRAM, and SDXL runs like a dream. I only have 48GB of RAM total, but VRAM is pretty much always the limiting factor (if I understand correctly, it works best when you have at least enough spare RAM as you have VRAM when you’re loading the model, but after that the computation is on the GPU if you have a 4090. Moving layers to the CPU/RAM drops performance fast). I have an A4000 in another machine that I was planning to add with a riser cable, and I just haven’t bothered because I didn’t end up needing it.
Leaving the upgrade path open is a solid choice. The space is so volatile that it’s impossible to predict what the requirements will be like in six months. They could even go down like they did when 4-bit happened.
I use an external DAC, so can’t speak to the whine there. They’re not that expensive though.