FWIW I've tried something similar but have given up after a few weeks.

If I recall correctly to get the wasm file I had to tweak the webpack config. Then there were issues with how Joplin loads plugins -- the main js file is loaded from one dir, while all other assets, including wasm, end up in another place. I had to patch Joplin to get around that.

EDIT

Had a look at my code, I've got this in my webpack config (though I'm not sure if that was my final version)

const pluginConfig = Object.assign({}, baseConfig, {
	...
	plugins: [
		...
		new WasmPackPlugin({
		  crateDirectory: path.resolve(__dirname, "wasm"),
		  withTypeScript: true,
		  outDir: "../pkg",
		}),
		...