They might be able to make requestable the connection requests to outside sources (which I expect is something many extensions use, even those without data collection), but whether those requests relate to data collection is not something that can be determined programmatically.
They should do manual testing to confirn/deny this, in a mystery customer sort of way.
They have the Recommended Extensions program, where they do that for a subset of the available extensions.
https://support.mozilla.org/en-US/kb/recommended-extensions-program
They should make it a requestable permission.
I’m not sure if that would be viable technically.
They might be able to make requestable the connection requests to outside sources (which I expect is something many extensions use, even those without data collection), but whether those requests relate to data collection is not something that can be determined programmatically.