The distinction here is choosing which version you want, not "the latest / maximum version the developer allows to be used for my device".

For example I just got an update to an app I've been using for a while. The update will sunset the app despite there being no online component to it. I'd kinda like to downgrade now, but the latest version compatible with my phone would be his sunsetted one.

What app are you talking about? I've never seen a developer set the "last compatible version" to something that intentionally breaks the app.

There’s also apps like Cooking Fever (the original is a great game to play with kids)

The latest version tacks on so many ads and “free to play” IAPs that it’s an entirely different game (and tbh one that’s no longer usable). It’s good enough and holds enough nostalgia for me that I would pay $2-5/yr to keep it clean but that’s not an option any more.

Thankfully I have been keeping backups over the years (iMazing) and so I was able to spend some time going through old versions to find a good one, but that is only a solution if you’re planning ahead or if you have a time machine.

Those versions don't stick around forever, unfortunately. A couple months back I reset my iPhone and it wasn't possible to download the Pebble app any more. My watch still works fine, especially with Rebble cloud services, but the app was just unavailable on the app store. That was the nail in the coffin that got me to switch to Android.

Again, you have to look in the purchased tab of the App Store. This allows you to continue to download apps you downloaded in the past that are no longer available as a new purchase.

You forgot the tiny universe of all the new apps you might want to try on an older device, what you describe only works for the apps you've already purchased

> new apps you might want to try on an older device

In that case, you borrow a newer device, sign in with your Apple ID, and download the app onto that device. Now that app will be in your purchase history and you can download the last compatible version for your older device.

This advice is as useful as "permanently borrow a newer device"

All you have to do is get the app into your user account's purchase history. You can do that on a borrowed device and immediately hand that device back to the owner.

...and do that every time for a new app. Again, "all you have to do" is buy a new phone

Apple keeps the OS current on it's devices for twice as many years as most Android device makers. Are we pretending that the sort of person who keeps the same device for up around ten years is the sort of person who constantly loads new apps?