Yes, you are correct. My initial post left out part of the path and the need to copy the json files, sorry. Here are correct instructions for others:
You can get the sounds for the TBM to work by doing this:
1. Go to C:\Users\[USERNAME]\AppData\Local\Packages\Microsoft.Limitless_8wekyb3d8bbwe\LocalCache\Packages\Official2020\OneStore folder and create the following folder structure inside the OneStore folder: asobo-aircraft-tbm930\SimObjects\Airplanes\Asobo_TBM930.
2. From your MSFS 2020 installation \Official\OneStore\asobo-aircraft-tbm930\SimObjects\Airplanes\Asobo_TBM930 folder copy the sound and soundai folders to the Asobo_TBM930 folder you created in step 1. ( full path to copy files to:
C:\Users\[USERNAME]\AppData\Local\Packages\Microsoft.Limitless_8wekyb3d8bbwe\LocalCache\Packages\Official2020\OneStore\asobo-aircraft-tbm930\SimObjects\Airplanes\Asobo_TBM930\ )
3. From your MSFS 2020 installation \Official\OneStore\asobo-aircraft-tbm930 folder copy the layout.json and manifest.json files to the asobo-aircraft-tbm930 folder you created in step 1. ( full path to copy files to: C:\Users\[USERNAME]\AppData\Local\Packages\Microsoft.Limitless_8wekyb3d8bbwe\LocalCache\Packages\Official2020\OneStore\asobo-aircraft-tbm930\ )