Group policy to set managed storage for an extension in Chromium Edge for Mac

nikrolls It actually works exactly like in Chrome.
You need to define the schema of the storage you want to use (detailed here https://developer.chrome.com/apps/manifest/storage#manifest).
After that you need to add the correct registry value like this:
[HKLM\Software\Policies\Microsoft\Edge\3rdparty\extensions\{YOUR EXTENSION ID}\policy\]
"objectFromSchema"={"prop1":"value1", "prop2": "value2"}