There are too many variables to give any sort of guidelines around servers. It’ll be up to you to do capacity planning.
I wouldn’t say minimal load. It could be anywhere from minimal to reddit hug-of-death load. You’re taking user input (from the bot) and storing it. Imagine every user in chat simultaneously guesses a score. Can your service handle that from a storage perspective as well as command processing perspective? Imagine someone spamming hundreds of guesses. Even if your bot doesn’t allow that, you still have to do something with the request. The users are sending the commands from Twitch, so you don’t have to worry about that. You do have to worry about once the request gets to your bot and service.