The best way, would be to import the Stickers from an url like https://tlgrm.eu/stickers/CatPusheen and save them to the Rocket.Chat database. And a button next to the Emoji-Button in the chat to select a sticker from the downloaded sets.
We've seen some companies reaching out to offer this, but we don't yet know how we're going to make this available. Either through apps or directly in code, or something else.
It would be very cool, if you could use the Stickers from Telegram
https://tlgrm.eu/stickers
The best way, would be to import the Stickers from an url like https://tlgrm.eu/stickers/CatPusheen and save them to the Rocket.Chat database. And a button next to the Emoji-Button in the chat to select a sticker from the downloaded sets.