But yeah, to basically securely configure your home you should treat the network your Smart Home Wifi devices connect to as untrusted. Some routers basically provide a separate SSID exactly just for this or allow for configuring separate VLAN. You don’t really know what they have installed nor is there a general open standard you can root or flash, each is usually its own Chinese rebranded proprietary mess.
There’s Home Assistant to allay some of the concerns: https://www.home-assistant.io/developers/license/
But yeah, to basically securely configure your home you should treat the network your Smart Home Wifi devices connect to as untrusted. Some routers basically provide a separate SSID exactly just for this or allow for configuring separate VLAN. You don’t really know what they have installed nor is there a general open standard you can root or flash, each is usually its own Chinese rebranded proprietary mess.