In case anyone stumbles upon this, i've finally understood my mistake: turns out that, while my @ActivityContext injection into my AuthModule was OK, I was still trying to inject the module in ViewModel, which means it would indirectly hold a reference to the Activity, and thus Hilt wouldn't allow me to inject it.

My somewhat ugly solution was to just inject my module into the Activity itself, since I have only one, and then pass the module as a reference down to other composables, and THEN finally pass it down to the ViewModel so it could make its things

@AndroidEntryPoint
class MainActivity : ComponentActivity() {
  @Inject lateinit  var authService: AuthService
  // ....
  AuthScreen(authService = authService, ...)
}