MicrosoftThis is by far one of the more complex Edge policies that I've come across 
It makes a lot of sense to implement and great to have this level of flexibility but so far I've hit a few hurdles and was hoping someone could steer me in the right direction.
In my example I'm simply trying to suppress the following prompts for Excel/Word:
Using the following JSON:
[{"allowed_origins":["live.com","office.com","sharepoint.com"],"protocol":"ms-excel"},{"allowed_origins":["live.com","office.com","sharepoint.com"],"protocol":"ms-word"}]
I've pulled the protocols from those defined within Default Apps | Choose Default Applications by Protocol but I'm not entirely sure if these are correct as the example from https://docs.microsoft.com/en-gb/DeployEdge/microsoft-edge-policies#autolaunchprotocolsfromorigins is a little ambiguous. The example JSON includes the protocols spotify, outlook and teams yet none exist on my W10 1909 /w Microsoft 365 Apps for enterprise (16.0.13029.20460) [current channel] - also as DidiHai76 mentions it's msteams not teams. Granted I don't have Spotify installed but on my device the application Outlook utilises the protocols FEED, FEEDS, MAILTO, STSSYNC and WEBCALS and the application Excel is referenced only for MS-EXCEL. In any case experimented with both ms-excel/excel and ms-word/word.
As far as ensuring all the usual culprits of group policy, I've added the JSON into the "Define a list of protocols that can launch an external application from listed origins without prompting the user" policy by way of the updated ADXM and verified it exists within the AutoLaunchProtocolsFromOrigins REG_SZ value in the "Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Edge" key as well as confirming it appears within edge://policy/. I'm testing with (Edge Stable 85.0.564.41 and current admx).
Note: Anyone unfamiliar with JSON (like me) who needs to both validate and convert to a one-liner that GPMC will accept, I've used https://jsonformatter.curiousconcept.com.