Can I access iTunes to download more songs on my iPod 7

No one here is able to suggest a value because it will sell for whatever someone else is prepared to pay for it.

As for the music on it, that effectively has no value because an iPod owner does have own the right to sell the music that's on it (that's Copyright Law). The recommendation is that an iPod should be wiped clean of all music and all data on it before giving it away or selling it. The following Apple article gives more information about that: What to do before you sell, give away or trade in your iPhone or iPad – Apple Support (UK).

You, or anyone to whom you pass on the iPod, can use iTunes, the Apple Music app or (on a Mac) Finder, to manage it. One of the first things that iTunes (and the other apps) will do is ask if you wish to delete all the music that is currently on it. Until the user answers "yes" to that question, the user will not be able to synchronise any more music to the iPod.

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To be clear about this, an iPod owner does not have the right to sell or give away the music that he or she has purchased. Apple have a procedure for wiping the content from an iPod before disposing of it.

There is finer detail to this (mainly centering around the original owner not keeping any copy of the music that he or she originally purchased), but the accepted position with digital copies on an iPod or in iTunes is that such copies cannot be sold or given away.

In the end, it is down to you to ensure that you do not infringe Copyright Law. The music industry has been known to go after individuals.