The library doesn't always fit, let alone larger keychains. This gets you encryption but means you have less room for the software that pays. This is the bala

The library doesn't always fit, let alone larger keychains. This gets you encryption but means you have less room for the software that pays. This is the balance. Also, many of the IoT devices have a few hundred bytes of ram and a few kilo bytes of flash, so public key may be out of the question. It is changing, there are devices like the esp32 that can fit a lot more along with providing wifi/bluetooth