Again, the problem is not Wi-Fi or that the devices use Wi-Fi to communicate. The problem is the protocol that they are communicating with. You can’t immediately say that any Wi-Fi smart home device is inherently bad just because it uses Wi-Fi. Wi-Fi is synonymous with cloud control, but more and more products are including Wi-Fi and local control, including some official standards like matter and MQTT.
I’m not sure if home assistant allows you to create a virtual thermostat entity or something like that using a separate temperature sensor and smart relay, but if it does, then this will work.