I have a name of the environment embedded into the app component like:

<app-component env="dev" />

I need to get some configuration from the backend based on this attribute on the app-component.
This config has to be in place before any other call to the backend happens (since they all use this config).

What/when is the best way to handle it?

Is APP_INITIALIZER a proper way to do it? Or does APP_INITIALIZER happen even before I can access app-component attribute?

The other option I can consider is just a global js/ts variable within index.html.
The third option is a resolver/guard on / route.