Q: iOS 6.1.6, how do you search for compatible apps in iTunes or search by iOS?

The problem is that very few apps that run on such an outdated iOS as 6.1.6.

The majority of apps today require iOS 7.0 or later.

Apps from the iTunes store can only be searched by name.

To more easily find compatible apps:

iOSSearch - search the iTunes store for compatible apps.

Apple Club - filter apps by iOS version.

Starting when iOS 7 was released, Apple now allows downloading the last compatible version of some apps (iOS 4.2.1 and later only)

Install the latest compatible version of an app on an earlier version of iOS or OS X

App Store: Downloading Older Versions of Apps

You first have to download the non-compatible version on your computer. Then when you try to purchase the version on your iPod you will be offered a compatible version if one exists.