I've seen it done (multiple times). I worked for a set top box manufacturer where the lead engineer wrote an OS and a GUI system, from scratch, for our platfor

I've seen it done (multiple times). I worked for a set top box manufacturer where the lead engineer wrote an OS and a GUI system, from scratch, for our platform in less than a year. It had a bunch of syscall personalities. One for vxworks so we could port stuff from our existing platform and one for Linux so that people could write drivers for it based on the O'Reilly Linux device drivers book (which was current at the time). It also had a couple of others for odd things that we needed. It was incredibly well written. It only took me a couple of weeks to port it to PowerPC and the first week of that was just phaffing getting my cross compiler working properly. In contrast, we had another couple of programmers trying to write a web browser for that platform. After a year they had something that could render primitive web pages but there was still a good chunk of the web that didn't work "quite right". After two years they were still in a similar position. Operating systems are a dark art, and the person who wrote Serenity is very talented, but OSes are, at least, a tractable and well defined problem.