@danialbehzadi It is currently WIP, if you try the Nheko master branch. It is based on https://github.com/matrix-org/matrix-doc/pull/2545 and currently needs a few manual steps of adding events to your account data. Should be much easier in 2 weeks. ;-)
For example you can just join matrix:r/nico's-stickers:neko.dev and use the stickers in that room, but to use them globally you need to send an im.ponies.emote_rooms event via devtools (currently).
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