BackboneJS application to Flutter migration. Which design pattern to use?

We have developed an application using BackboneJS. Now we are planning to migrate this project using Flutter.

Our Project folder structure is like below

Navigation from one view to another happening at root level, sub-levels(Eg: Jobs, Modules in the above screenshot). We have to trigger notifications between multiple classes.

We are planning to support all 3 platforms (iOS, Android and Web) Could some one suggest me the best architecture or design pattern to implement this BackbnoneJS application in flutter.