If I did that half my neighbors would own my devices in a week because they like transmitting open access points for setup purposes. I just connect them anyway and then just block them from outbound access at the router if I want to restrict them. That way I can be sure. Then I can use my Homeassistant server to control them from behind the firewall locally if they have that capability.
They are anything but. Somebody with a laptop and a $20 USB SDR stick can see every piece of text flying though the air.