Unfortunately can't take credit on iOS here - the same app is 1.4mb on iOS - I assume because it isn't statically linking some part of the CloudKit syncing framework on macOS whereas it does on iOS? Or maybe SwiftUI framework is dynamic on macOS due to Catalyst - not really sure.
I copied an app from the App Store. Their business model was free desktop application but $20 for the iOS client and I really wanted it so I made a 'clean-room' implementation with CloudKit and charged $0.99 for a one-off cross platform sale.
Bit brazen, but the idea isn't entirely unique.
Edit: P.s email me at adam@adamfallon.com if you would like a promo code to get the app for free :).
I wonder if Google does anything to accurately reimburse something like ad-naseum* clicks. I imagine the probably take up a non-insignificant amount of spend at the $6m level