Wouldn’t it be easier just not to upgrade older phones and not allow phones running older OS’s to download the last compatible version of an app?
Around the time of iOS 7, Apple started letting older versions of iOS download older version of apps that were compatible. Even today you can take a first gen iPad running iOS 5 and download apps that have since been upgraded but where there is an older version available.
I reset my old iPad 1 about two years ago and redownloaded Netflix, Hulu, Spotify etc. They all still work.
Around the time of iOS 7, Apple started letting older versions of iOS download older version of apps that were compatible. Even today you can take a first gen iPad running iOS 5 and download apps that have since been upgraded but where there is an older version available.
I reset my old iPad 1 about two years ago and redownloaded Netflix, Hulu, Spotify etc. They all still work.