UPDATE: About an hour with Claude gave me this: https://3dmmex.pages.dev/
It actually works reasonably well from what I can tell, though I haven't thoroughly tested it.
Here's the WASM source to those interested: https://github.com/Tombert/3DMMEx_WASM
Here's the WASM source to those interested: https://github.com/Tombert/3DMMEx_WASM