Based on my IoT devices I already have, any device that supports Matter will probably use Wi-Fi to ping back home whenever they can.

From the actual announcement:

> Wi-Fi enables Matter devices to interact over a high-bandwidth local network and allows smart home devices to communicate with the cloud.

If only there was a way to have it explicitly NOT communicate with the cloud. That's the last thing I want.

I generally just block external internet access for smart devices on my wifi, but it'd be really nice if I didn't have to.

My AmpliFi router did this the other day. It added itself to HomeKit to create device specific firewall rules for iot devices on my network. The options were like “access everything, access whitelist of services, no access”. I turned on the whitelist but it broke everything :D

It’s the same as it always has been. You need to check in advance, if it’s an extra dumb device requiring internet or not.

Not necessarily, because Wi-Fi is energy hungry and it will empty the battery in a short time. The Wi-Fi enabled CR123A battery powered Shelly devices I have exhibit shorter battery life than Zigbee devices operating on a CR2032 or CR2450 and the battery holds many more mAh. If yuo have an outlet or cable powered device then yes, they usually phone home.

I suspect a big part is to allow bridges like the new IKEA hub. Lots of folks put those in wifi.