The solution is not more but different connected devices so I can decide for myself what needs to be connected and by which protocol. Get the dumbest device on the market, no wifi, no internal clock, maybe not even a humidity sensor and then, if and only if I need to remote control it, for example to put it on a schedule, I can use the cheapest “smart” device on the market to connect it to an in-house machine that can turn it on and off.
Sadly, many wifi-enabled devices only work with some proprietary cloud-service and even if not, they’re only one configuration error (or intentional backdoor) away from talking to the outside. Better have something that isn’t physically able to talk to the internet no matter how badly I fuck up its configuration and my firewall.