Q: My ipod cant update to the new ios because of age does this mean i am no longer able to download apps like snapchat?

Many, but not all, apps offer older versions. See: App Store: Downloading Older Versions of Apps.

(Note that I am affiliated with that site, and some pages contain ads).

1. The fourth generation iPod touch can run 6.1.6.

2. Click here and try following the instructions.

(126298)

It means that you are not able to download any apps made for the ios update that you can't download

I have an old device.

Some apps do work. (the older version is available to download or the new version is compatible)

A few apps would not work at all even if you could download them.

To answer your question, you can still download apps.