I can’t speak about VR, but I have built a PC (9800X3D / 5090 / 96 GB) in the past year to run MSFS 2024 on triple 4K screens. In doing so I learned a lot and did some benchmarking which may help you to get a general sense of resource usage at various settings levels.
The issue for your budget is obviously the GPU and cost - 16 GB VRAM is accessible, but going to a 32 GB 5090 uses up your budget. The previous generation AMD RX 7900 (RDNA 3) has 24 GB but may be limited in other ways (like missing out on the newer FSR technologies for RDNA4). And going to the 32 GB RTX 5090 eats most of your budget. The yet to be released 24 GB RTX 5080 Super might be worth waiting for… but once it hits the market, the demand may be insane causing insane prices for a while.
Here is a chart of some testing I did in May (SU5) of the A330 at KFJK using each DLSS Anti-aliasing mode, each at the Low, Medium, High, and Ultra Global Preset, on 2K and 4K screens. You can get a general sense of FPS, RAM and VRAM usage.
(disclaimer, not scientific, and every pc is different. Full test description in this thread)
For example, in 4K, DLSS Performance (Preset M) with Global graphics preset High yeilds really good results under 16 GB of VRAM. From there you have room to customize TLOD and OLOD a bit, and so on. (I would suggest that 60 FPS is a sweet spot, whether native frames or 30 with 2x frame generation, which I use - any extra resources I spend on increasing TLOD/OLOD, not FPS).
Of course you can get better with more VRAM, but the cost might be prohibitive.