Google says "If you're building a Progressive Web App, consider using a service worker so that your app can work offline."

What does "consider" mean here?

And I'm pretty sure SPA is also not a criteria for PWAs, it's just a suggestion.

And also, the install banner is not really yours, it's the browser's functionality.

Per Google:

> Chrome uses a set of criteria and visit frequency heuristics to determine when to show the banner.