Wouldn't that require making and maintaining separate versions of the app for every possible subset of permissions? That sounds like a nightmare not just for DDG but also for new users that have to figure out which version they need to install.
No: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/Web...
> Use the `optional_permissions` key to list permissions that you want to ask for at runtime, after your extension has been installed.