> - A lot of blast damage can be contained if home devices use local / MDNS based service discovery as opposed to Internet based services. Many services could then either choose to reply locally or sometimes relay to the Internet if users policies allow. Unless people want other people unlocking their doors through the Internet, and they explicitly say it, Internet connection can not be mandated.

Networking ignoramus here. Are you suggesting the device could be prohibited from accessing the internet directly, and would be required to relay through a separate device (presumably with better security assurances)? Because that sounds like a good idea.

Are there off-the-shelf firewall (or whatever) products that do this already? Quarantine the IoT devices and limit them to whitelisted, curated endpoints?