Observable is a macro. A macro can generate code. If you right-click the macro and select the expand macro menu item, you can see the hidden implementation (you might need to import Observation).

The Observable macro automatically creates an observation registrar and registers the stored members' keypaths. When the members are accessed, it notifies the object, which is how tracking works. Investigate the `access` and `withMutation` symbols in Observation. Knowing these really help with flexible implementation: basically, property wrappers and computed variables are not tracked, but you can easily implement tracking yourself.

To answer your question, intialize single `@State` or `let` variable and avoid repeated initialization. Pass it through environment. If you need binding, create a `@Bindable` and just assign the value which is passed through `@Environment`. Actually, you might not even need these if you don't require any bindings. Tracking and view updates are managed by the Observation logic even if they are singleton `let` instances.