Here is an outlined approach to PWA implementation for a Drupal site, but other options are certainly available with similar designs.
HTTPS is a prerequisite for progressive web apps. A service worker is only able to be installed on sites that are served as HTTPS. For this reason core’s support for HTTPS needs to be further improved, continuing the great progress made over the past few years.
Source: PWA :: WordPress.org
This is an interesting development. If successful including this functionality into WP Core would turn every WordPress site into an app. That would be fun.