Javascript on the browser was the only choice for your frontend code, however, WASM is already shipping on all current browsers except IE and Opera Mini (which is a miniscule percentage of browsers in use today).
It is just a matter of time where WASM becomes the ABI of choice for crossplatform app development as the binary deployment vehicle where you can program in any language and have the app delivered as a WASM package via HTTP/HTTPS.
Apple's App Store moat will dry up when people (esp. devs) realize that they can get close to native performance for web apps delivered this way and the vanity of an icon on the phone/tablet screen isn't worth forking 30% to big apple.