Add offline mode to a Flutter Web App - Service Workers/Pwas

I need to transform a Flutter app into a PWA and I'm trying to understand if this is possible without rewriting the code in AngularDart.

I did some research and I found out that first I need my Flutter App to become a Flutter Web App but nothing more.

There is also a StackOverflow question that speaks about this but answers are not complete

How to transform Flutter web app into a PWA?

I found some PWA examples with AngularDart, JS, etc... but nothing about a Flutter PWA.

*On the Flutter for Web homepage they mention PWAs but I didn't understand if it is already a feature or not.