should I choose WatchKit companion app or Standalone watch app

Question

I have an iPhone app that is published to the App Store and I'm now looking to add a watch extension

My question is, do I choose companion app or a standalone watch app?

the watch app will work independently of the iOS app, but will also rely on the iOS app to send data across to it

To give you a brief summary of the functionality I'm looking for, The IOS app is a workout app, and has a number of user created workouts on it. I would like the user to be able to send one or more of these workouts to their watch, so they can leave their phone at home and workout solely from the watch app

obviously the watch app will need it's own independent CoreData model, which leads me to think I would create a standalone watch app, so I have access to the WKExtensionDelegate and WKHostingController, to initialise my core data

is this the right approach, will the watch app and iOS app communicate with each other if they are both standalone, or would I need to create it as a companion app?

I've searched the internet for hours, but can't find a definitive answer

thank you in advance