Does Firefox support Progressive Web Apps (PWAs)?

No, Firefox does not support progressive Web Apps

Progressive Web Apps (PWAs) are web apps that use web APIs and features to provide a native app-like user experience.

Firefox supports many of the PWA APIs, but it does not support the functionality to install them as a standalone system app.

However, you can use an extension called Progressive Web Apps for Firefox to install, manage, and use PWAs in Firefox.