Paste the store links, or just the IDs. One store is enough.
From apps.apple.com, or the number after id.
From play.google.com, or the package name (com.example.app).
Neither store can install on a computer; pick the page they see.
The link only ever sends people to the App Store or Google Play page for these IDs, so it can't be changed to point anywhere else.
One link for every phone.
https://hiyaly.com/go/app?ios=570060128&android=com.duolingo&web=ios
Ready. iPhones go to the App Store, Android phones to Google Play.
Smart link
https://hiyaly.com/go/app?ios=570060128&android=com.duolingo&web=ios
App Store
https://apps.apple.com/app/id570060128
Google Play
https://play.google.com/store/apps/details?id=com.duolingo
Phones are told apart by their browser's user agent. iPads on recent iPadOS say they're a Mac, so they follow the computer choice. Free, with no account, and the link keeps working as long as your app is in the store.
Free App Store Link Generator by Hiyaly