One of my first jobs as a junior programmer in the 80's was to build a multimedia engine that would boot both on CGA and EGA (and then, later, VGA) systems, was not allowed to use any MS-DOS calls (BIOS and pure assembly only) and it had to run the same bytecode scripts for the programs being made with the engine, seemlessly.
It had a compiler for the script, a bytecode interpreter and VM, and different HAL's depending on the system in use, with the VM being used to play what were then called "multimedia" titles - graphics and text and sound, all on the same screen. This all had to be done by me, a lowly junior, and when it was finally delivered and titles were shipped, I moved on to other things .. an online version of the engine that could get its bytecode over ethernet .. and I had to write all the drivers and HAL code myself.
Sure, this was the 80's and programmers were a different breed then, but it always bugs me when Mr Special 21st Century Comp-Sci Grad comes onboard to his first ever 'real' job and yet .. has no idea how to even find the compiler on his system, let alone build one himself.
There is a deleterious effect with the computing industry, which happens whenever the New Cool Shit™ hits the scene - everyone forgets the Old Cool Shit™ as fast as they can - but, inevitably, eventually, you are gonna have to learn how to write a compiler, kids, and build a VM/ecosystem around it, at the very least. (Or just use Lua, lol...)
When I first encountered TempleOS, I wasn't as impressed as my peers - this is just how we did things in the 80's - but what was impressive was the persistence he exhibited in extending TempleOS in spite of the great personal suffering under which he clearly labored ..