Since the OnHub only comes with Ethernet you'd have to put something between it and the wire anyways of course, but it then has to be more than a dumb modem, and you'd be forcing all traffic through the tunnel.
IPv6 isn't without problems, but many people use it without noticing, through consumer devices way cheaper than this. The ones complaining the most are the enthusiasts which suddenly can't reach their home server via IPv4 anymore.
Yet another device Google will sell, and then discontinue in 24-36 months.
You don't know that.
I've been burned, and I refuse to purchase yet another Google device for a market they're just testing the waters in. I'd rather spend my money with someone who needs it to support their product, and that product is their business.
Chrome devices have 5 years of updates guaranteed. I have a cr-48 from 2010 which still gets updates (currently on -dev 56). How many times has there been a story on HN about RCEs unpatched for months or years in consumer routing gear? The fact that you purchased that hardware doesn't seem to be sufficient incentive based on the record. But when you have an incentive of a secure and performant internet, and also have the talent, infrastructure, and existing codebase to make something work and work well, you have economies of scope that make supporting it much easier and cheaper.