That's a 5th generation iPod from 2012. It cannot update beyond iOS 9.3.5, and yes, most apps now will not work on it. Its simply too old at this point for any current apps in the store.
You may be able to get compatible versions by downloading the apps from your purchase history instead of the directly from the App Store entries. But be aware that Apps old enough to run on iOS 9.3.5, may no longer work with their associated services.
click here ➜ Redownload apps and games from Apple - Apple Support
Its probably limited to playing music and not much else at this point to be honest.