I am 99.99% sure that less than 20% of Australian graduates could do this, and honestly I wouldn't be surprised to hear that the actual answer is <1%.

I was studying at Monash, which is considered a solid university here, and holy moly are the standards low. I had classmates in the second year of my machine learning postgrad asking me things like "What is machine learning?", and they all graduated and found jobs anyway.

Hmmm here at least in my uni in Argentina, we have an obligatory computer architecture class and we implement a protected-mode x86 (32 bits) kernel with interrupts, paging, etc. We obviously get some guidance but it's not that hard if you read the docs, nowadays you don't even need to go deep into the Intel manuals probably since osdev wiki has a lot of content.

Besides it's much easier nowadays, if something's wrong you can feed ChatGPT your GDT definition for example and find out if you misplaced a value, which used to be a PITA to debug.

As the parent comment says, I think the path to a booting usermode kernel has long been beaten, it's not trivial but it's not that hard either, I believe the impressive stuff is once you get out of "tutorial land" and implement a network stack, or a UI stack, etc.

I'd agree with this. I did a double degree in Comp Sci/Comp Sys Eng at RMIT (1998-2002) and even from that era I would say that's largely true. Out of the people who did my course (and those I knew from other degrees like Comp Sys Eng/Business) very few are still doing deep technical programming for a career and/or hobby programming on the side on deep technical non-web things. The rest are mostly working for places like consulting companies, banks, big data, Telstra, etc in management roles like project manager, scrum master, solutions architect, change management. A lot of folks I think were just not that interested in stuff like writing an OS, how does virtual memory work, how does the hardware work, etc so they gravitated out of those software development roles into management roles. Nothing wrong with that, but I just think not everyone is interested in or capable of writing an OS!

What did they find jobs in? Australia has like one tech company.

Which is odd since their universities have built two of the most interesting CS projects I can think of (Mercury and L4). And WWWJDIC I suppose.