as others have pointed out "just" is doin big overtime here. but also x86_64 saps the fun out by forcing you into archaic irrelevant details IMMEDIATELY. but really, it's a good filter

making toy os for a nice small board on a nice architecture like riscv is night and day more enjoyable. not that modern boards that have more device tree overlays than senses are a good starting point either.

a more modern mmix that builds further up, or nand2tetris, xv6 or any other riscv project going all the way to a user mode ui would be really cool