I built https://www.CheckYourList.app originally for myself for spontanous checklists that I go through regularly. Happy to say it just passed $500 a month recently :)
All SwiftUI, it is built within Apple's iCloud ecosystem using core data. It's a great way to get an app up and running with sync very quickly, but then you are stuck on Apple's platform.
I've been thinking about doing an iOS app for awhile now.
Does this have a backend of some kind? What's your tech stack? All SwiftUI, or Expo/React Native?