Since the WiFi is the only source of emissions, you can avoid FCC certification by using a pre-certified module like an ESP8266 or ESP32 or one of the many offerings from TI.
You cannot skip FCC certification, you can just go through the "simpler" unintentional radiator testing when using pre-certified modules. That's still around 1.5k USD.
Also you can't use custom firmware on a pre-certified module, otherwise you'll still have to do the intentional radiator testing. You control those modules with an external MCU, which is cheap though.
TIs WiFi offering is horribly expensive compared to any ESP8266 based modules, still like 13$ @ 1k units on DigiKey. That's the main reason the latter got so famous.
You need to sell a few hundreds just to get those fixed costs down to a reasonable amount per unit. And then you still have to pay the engineers... Maybe 80-100$ per unit would be more appropriate, but then again I doubt they sell in huge numbers.
