Felix can you please take a look?

I would hold off on implementation pending some investigation into sites with disjoint ServiceWorkers. That seems legitimate and this would prevent them from getting a WebAPK.

Meta: I also think we should strive to keep the criteria for the banner prompt, WebAPKability, and the Lighthouse section "User can be prompted to Add to Homescreen" in sync.

+Owen, who should we coordinate with on lighthouse?

This is an older bug (predates a lot of the discussion on what constitutes an app). Given that this isn't covered on PWAList/Lighthouse, I don't think we want this. We can re-open if/when that changes