Hi @patoupatou,
Our APIs only let you upload one at a time right now, but as long as you don't hit the rate limit on your server (defaults to 10 requests per second per user, I believe), you'll be able to use the api/v3/emoji/create API route. We don't have any Python drivers at this time, but we do have Javascript and Go drivers that you can look at for an example of how to use the API.