You could read the main linux kernel git log and see who the top contributors are.

If you prefer system level programming there are jobs out there and plenty of work to do. I dunno if this counts as, "hardcore engineering." To me, engineering, involves many other skills other than writing code: being able to specify systems clearly and, as the occasion demands, formally is a part of engineering; communicating with others; Knowing which trade offs to make depending on a situation, etc.