There are fiber PON/ONU/UT/$JARGON in shape of an SFP module, though most customers don't appreciate such offering and therefore it'll be an upsell.
As for why not USB specifically, probably because such a device is inherently much faster and responsive in upload to the Internet than downloads, and therefore it makes less sense.
As for why not USB specifically, probably because such a device is inherently much faster and responsive in upload to the Internet than downloads, and therefore it makes less sense.