Ah, I just found an interesting article @
https://www.thebookdesigner.com/2013...-use-my-fonts/
It says if you're subscribed to Adobe Cloud (which includes Dreamweaver, Photoshop, etc.), you can legally use their fonts in an epub. That rang a bell; I think I remember reading that long ago.
I'm a little confused regarding which fonts are part of my Mac operating system versus which ones belong to Adobe. However, I assume that anything I access via Photoshop is an Adobe font.