hmm.. yea you need kiwi browser that can handle alby extension, then be logged onto your npub w that on that website
then you can just add whichever emoji packs you see.. auto synchs on amethyst
if you long press the emoji react button (and not a too old version of amethyst running) they should appear in screen.. then you can add them like you do w normal emojis
idk bout other clients and that website tho