This is a really nice idea but considering we haven't even solved the relatively simple case of users giving permissions to apps and expecting them to behave responsibly, I'm not optimistic that we can solve the much more challenging case of importing library code.

e.g., If someone gives an app the ability to upload photos, it can silently read all photo metadata, upload all photos to a private server instead of uploading just the single photo that the user picked. This can be solved with OS level standard photo pickers but it hasn't been yet.

Same with package code. Maybe a package needs network access for stuff it genuinely needs to do. However it can (and probably will) at some point go above and beyond in the amount of data it collects. FB Mobile SDK outage is a good example of this. https://www.bugsnag.com/blog/sdks-should-not-crash-apps