You can also try oculus airlink. You can activate it inside the headset settings.
You do need a good wifi 5 connection though.
Works better for me than Virtual Desktop.
Once airlink is established with your computer you can go into FS2020 and hit Ctrl + Tab to enter VR mode.
@OP,
With Virtual Desktop, you need to start SteamVR and start with maybe 120% video resolution. Then on the SteamVR settings Developer (I think) TAB, select SteamVR as OpenXR active runtime (MSFS is OpenXR). Now, you can CTRL+TAB and connect to MSFS.
NOTE: I prefer Airlink @200Mbps/3648EncodeWidth/ASW45/SS=1.6/FOV0.75;0.75/Sharpening=Enabled