A bunch of devices don't... IoT devices based on esp8266 or esp32 don't (from washing machines to sous vide cookers), many ip cameras, sensors, smart locks etc.

A bunch of devices don't... IoT devices based on esp8266 or esp32 don't (from washing machines to sous vide cookers), many ip cameras, sensors, smart locks etc., don't. Yeah, linux itself might support it, but when compiling the image for those few megs of flash, developers just disable it, because well.. everyone still has ipv4 available.