We've had amazing stories so far with Progressive Web Apps and that's just great. They work for every user, regardless of browser choice because they're built with progressive enhancement as a core principle.
When thinking about Progressive Web Apps think of the entitre app cylce. From how you deliver resources at your backend to how the pwa looks like when the user interacts with it.
Users do not care about what actually is happening at the backend of your web app or just any app. What they see and how their goals are fullfilled on your web app is king!