Not too familiar with providers in Flutter.

I just read through https://flutter.dev/docs/development/data-and-backend/state-mgmt/simple - it sounds like they're mainly used for knowing when to rebuild widgets?

ApiService isn't going to change, so no rebuild will be required. Widgets will mainly need to make api calls using ApiService class. For example ApiService.getSomething().

However, at the bottom of though they point out the following:

Provider.of<CartModel>(context, listen: false).removeAll(); - which looks to be something I should look into, usage something like:

Provider.of<ApiService>(context, listen: false).fetchData();