If he's going to spend some money, then there are some choices required. First of all, it's really important to decide whether he wants to capitalize on his prior experience with the PC. I don't know how transferrable his knowledge of coding is to ARM, ARDUINO, or other cores/platforms. I simply believe that he first has to decide whether his emphasis is going to be on coding, which any platform will easily support. If, however, his principal interest is in hardware, by which I mean building a circuit, not just applying features already built into the components involved, e.g. I2C, SPI, PWM, etc, not that those aren't important.

If he starts with a bare perfboard and a raw MCU, he has to learn/experience one set of things, while, should he choose a ready-made application, e.g. the 'F120 board from SiLabs, which I do like very much, he'll learn and experience a wholly different set of things.

It's just a choice he, and not we, will have to make. He'll also have to decide how much money should be involved. We can't do that for him either.

RE