smart door lock

I'm just curious, how exactly does a smart lock, or a light bulb or a smart kitchen appliance pose a threat? If you have your router properly set-up, disabled UPnP, enabled the firewall and no port forwarding, then there's no way some remote hacker can enter my home network through a security...

I’m a new fan of smart homes! What are your thoughts on getting a Google Nest Hub? Are there better alternatives to this device? Any idea on where I can get them at a steal price? Thanks in advance.