I had tried going down this path but my performance in MSFS when using SteamVR as the runtime is horrible. It was with the Rift S and it still is with the G2. So, any app that relies on SteamVR is no good for me to try to use to bring a desktop into MSFS.
BUT, I was working with another guy on Facebook to try to figure out how to do this and I finally realized that it’s not all the difficult. It’s not ideal, as it brings in a whole desktop (monitor) rather than individual apps and you have to switch the mouse in and out of MSFS. But it works with no performance penalty and does not need Steam.
The other guy made a video of basically how to do it (you use the desktop from WMR), with some good tips. He uses a voice activation program for some things (like switching the mouse), but there are other ways.