There's a range of capabilities for sure, depending on how close you want your device to get to "This is a PC". Mbed, FreeRTOS, and the other small RTOS's are

There's a range of capabilities for sure, depending on how close you want your device to get to "This is a PC". Mbed, FreeRTOS, and the other small RTOS's are nice for what they are, but their support for more advanced things like multi-core operations, filesystems, multi-tasking and multi-user functions are still limited (and, IMO should remain so as they expand their support for lower-performance devices).