More like pi+[y]es, but single syllable and no y.
EDIT: Here are three audio files to hear: https://pl.wiktionary.org/wiki/pies#pies_(j%C4%99zyk_polski)
As an American, I hear “pyes” - a single syllable “yes”, with a preceding “p.”
When do you use that vs собака (sobaka)?
As an American, I hear “pyes” - a single syllable “yes”, with a preceding “p.”