The default is to only present a limited selection of addons that are reviewed by Mozilla for mobile compatibility and user experience. The way this is implemen

The default is to only present a limited selection of addons that are reviewed by Mozilla for mobile compatibility and user experience. The way this is implemented is by constraining the user to installing extensions that are in a particular Mozilla-managed addon collection. On Nightly (and now on Beta), you can use a debug-menu feature to override the ID of this collection with your own.