Ciao, this is the author, the implementation is in C gh:dyne/zenroom that we transpile in WASM, so available in js <3 But there are also other implmentations for sure like gh:dajiaji/crystals-kyber-js

Please look also at dohd https://dyne.org/dohd/ as an alternative I know both the author's, they are super cool! You can ask directly @jaromil@fed.dyne.org

Tomb on macos and Linux https://dyne.org/tomb