Most are DIY, anything that is low wattage can be turned fanless if you buy some parts and build it yourself. But OP was daft with his answer. As someone who doesn't like the Apple ecosystem and only uses PC, I can only admit defeat when it comes to power efficiency. There is no way you could make a true fanless system run as well as Apple's efficient SOCs. PC parts that are as powerful generate a lot more heat and even with the best fanless cases and radiators there is only so much you can do to dissipate heat.