I have my best results with RxJS when I deal with it in as strictly a functional manner as I can.
I am seeing some imperative flavor in the code of this thread - especially the tap in SettingsEffects and the aforementioned Promise of SegmentRouterService.
I can tell you this: the basic idiom described in this post does indeed work when subscribing in the app component - I’ve been using it for quite a while to update the enabled/disabled status of common toolbar buttons.