I saw the Lenovo S940 the other say, the screen is simply amazing, and the form factor is small as well. Although the flex of the keyboard is kind of disappointing.
Take a look at the MBA as well, it is larger/ heavier but it is still a very portable form factor and runs macOS. Failing that, the surface pro 6 is a 12.3" screen and the i5 version is fanless, with by all accounts decent enough battery life.
I meant to add that the Surface GO must be about the smallest device (10 inch) which will run a full desktop OS. When I got mine it made me realise how much I would love an iPad which could run full macOS.
I meant to add that the Surface GO must be about the smallest device (10 inch) which will run a full desktop OS. When I got mine it made me realise how much I would love an iPad which could run full macOS.