Is there a subwoofer that pairs with the HomePod? I can't find one. If not, that would make it a 2.0 system, which is a whole different thing. Also, it looks like stereo pairing is some ways off.
Any set up of Homepods isn't a 2.0/2.1 system. That's a new paradigm of speaker arrays and software based signal processing in order to eliminate the sweet spot associated with any stereo setup.