Recommended:
Interesting discussion: https://www.reddit.com/r/photogrammetry/comments/lcywo8/computer_build_for_rendering_of/
Meshroom can multi-thread on some nodes but not on all. So more cores != faster! https://github.com/alicevision/meshroom/issues/175
Multiple GPUs can be used if they are older to make Meshroom run faster. Although on newer GPUs there isn't much of a difference. https://github.com/alicevision/meshroom/issues/644
In this post, it is also mentioned that it is important to have one fast SSD. GPU is not that important because it is only used while depth mapping. I personally can confirm that. A GTX 1070 ti can go through this process kinda fast. An RTX 3080 would do the job just fine. https://www.reddit.com/r/photogrammetry/comments/jr58j4/help_with_meshroom/
Just some performance graphs and recommendations for another similar program: https://www.pugetsystems.com/recommended/Recommended-Systems-for-RealityCapture-228/Hardware-Recommendations
As I expected for multiuser remote desktop on Ubuntu xrdp is an option: https://askubuntu.com/questions/1292694/multi-user-remote-desktop-from-windows-to-linux-machine
But still, X11 would also work. I have experience with xrdp already and it works well enough for most tasks.