Maximum kudos to @mbucchia. Just tried the NIS scaler and it works brilliantly for gaining FPS. I had FS2020 tuned for decent image quality at 100% native resolution of my HP Reverb G2. But I had to trade off FPS for visual quality meaning I was only getting around 25 FPS (RTX 2080ti overclocked). But with the NIS scaler set to 80% render scale and 50% sharpenss (100% render scale in FS2020 and OpenXR custom render scale enabled and set to 100%) I am now getting 34 FPS without any observable loss of visual quality.
Thanks for making this. Now I have the VR flying experience I was always hoping for with FS2020.