Big fan of this author's work.
They have a Gameboy emulator written in C, which can be compiled to WASM and run in the browser.
https://github.com/binji/binjgb
I learned a lot from the code.
Also I love this project with a bunch of demos in hand-written WebAssembly Text (WAT) format, which is like low-level Lisp that works only with raw memory, numbers, and minimal syntax.
https://github.com/binji/raw-wasm
Then I discovered the same author is quite active in the WebAssembly ecosystem, including specs and tooling. Fascinating stuff!