Can a single “s” change the entire meaning of a keyword phrase?

To a human, yes.

But to Google it usually treats it the same:

The truth is a listicle ranking “wedding bands” also answers the singular version of the keyword (“wedding band”).

Although a Reddit thread from 7 years ago appears for the singular version:

Is this a sign of things to come? We’ll see, but one thing is for sure:

The SERPs change more than ever as Google tries to deliver the most relevant results. The days of setting it and forgetting it are over.

SEO Bite #2: You need to constantly monitor the SERPs in your industry and make adjustments at the same speed as Google.