I didn't find a difference between defining an @Observable class object with and without @State property wrapper. In the video, in order to fully adopt the new Observation framework, they emphasize to use only 3 property wrappers (although we can still use other wrappers as they are not deprecated at least today): @State, @Bindable and @Environment, so we can live (somehow) without @Binding, and YES, @State can be used with value and reference types although the docs say: Use state as the single source of truth for a given value type that you store in a view hierarchy, which's misleading.
Now if I want to live without @Binding and to create bindings to my struct data model's properties, I have to convert my struct data model to @Observable class, I don't know if this is the best available approach to fully adopt Observation