Fido security keys, Apple ID and iPod Touch

If I establish FIDO compliant security keys with my Apple devices running the latest OS version, where does that leave an iPod touch running 15.7.7?

I've read, "users who set up Security Keys with their Apple ID will be unable to log in to their account on older devices that can't be updated." And, "any device that can be updated to iOS 16.3, iPadOS 16.3, or macOS Ventura will work with Security Keys, but others won't be able to connect to a user's Apple ID account." (both quotes from B. Snyder, 2/4/23, www.screenrant.com, as well as others).

For me, the iPod Touch remains my music device, over all other Apple products. Is this going to disable the iPod as far as synching with the Music App on my Mac and other functionality like my Pandora account paid through Apple, or is this a non-issue as that functionality remains, just no access to the actual Apple ID account? It would be unlikely I would be down to only my iPod Touch as my only available Apple device in a login crisis.

Thank you,

Cy