https://github.com/google/music-synthesizer-for-android/tree... has an experimental port, but I'd consider it a starting point, not a polished web app.

ETA: there's also https://www.webaudiomodules.org/wamsynths/webdx7/ , but sound is pretty crackly on my setup :/

Can confirm audio is very glitchy. Chromium 80.0 on reasonableish i5 laptop.

Actually works quite well in Firefox for me (sometimes notes don't quite trigger right, but if it plays the sound it sounds ok)