HUZZAH! It works!
For those that might be stumbling across this from a google search. The magic I needed to apply was:
DracoCompression.Configuration = {
decoder: {
fallbackUrl: "3d/draco/draco_decoder_gltf.js",
},
};
DracoCompression.DefaultNumWorkers = 0;
This disables remote loading of the decompressor, disabled web workers AND disables WASM decompression.