Who handles support for this? Is it Google, or one of the carriers that Google's using? Who do you talk to if the handoff between carriers doesn't quite work? I've skimmed the FAQ and I didn't see that listed in there.

For context, I use Google Voice, and while it's really nice in a lot of ways, it has some unfortunate bugs that have persisted for years that it seems impossible to get support for. I no longer unconditionally recommend it to people because while being able to take calls from my computer and get transcripts of voicemails is great, it also pseudo-randomly decides to only direct some calls to devices where I'm not present with no notification on devices that I'm using and also drops a small percentage of texts (my guess is around 1%). Most people I talk to are horrified by the idea of texts getting dropped, and I don't recommend GV to those folks, although it's fine if that's a tradeoff you're ok with.

I understand that it's a beta and that bugs are expected, but it's a problem when you run into a bug that interferes with your ability to use your phone and there's no way to get support for it.

Phone carriers aren't exactly known for their stellar customer service, but at least with them, if you call back enough times or escalate to higher level support, you'll eventually get a resolution. As far as I can tell, that's not true of Google's phone related products.