If anyone uses the Microsoft Store version of FS2020 and wants to manually import it into PE under the “Imported” category, the game has no exe file.
And currently, PE does not import Microsoft Store games automatically (we will look into that).
But there is a solution:
Create a bat file to start MFS with the FastLaunch option which looks like:
C:\Windows\System32\cmd.exe /C start shell:AppsFolder\Microsoft.FlightSimulator_8wekyb3d8bbwe!App “-FastLaunch”
Then import the .bat file in PE (Add New Import)
(Thanks to @hashjime on the FS2020 forums)