I submitted and got the very first version approved for App Store. This version only has local storage of exercises and very limited functionality. But hey, it's a minimal viable product and I can share it with friends to get feedback.
My next step is to build the backend functionality and come up with a solution for connecting the watch app to the backend so I can display the users' progress in a web app. I have an idea for how to do this and will try to build the first version this weekend.
Watch Routine is available for download at (or just search for "Watch Routine"): https://apps.apple.com/us/app/watch-routine/id1570629663