I had the exact same thought. I vibecoded a MOS6502 emulator a few months back in Rust. My Rust skill is weak, and I learned absolutely nothing about the 6502 or CPU design. Had I done it manually, there's also no way to prove I created it without LLM help making the whole exercise less appealing overall.

A nand gate takes 2 transistors. So 554,000 transistors if this were manufactured in a physical device.

By way of comparison, the Intel i386 had 275,000 transistors.

I was about to say that's a whole lot of gates for not a lot of computer, but then saw that rom and ram are also an array of nand gates.