Hey friend, sorry I misunderstood the original question. I still think a standalone page might help, but like you said, you really want to put a firm boundary down that this is for fun not open for commissions.
Maybe something like "I'd love to be able to help with this request but since this is my hobby and not a business, I'm not equipped to handle requests like this". Feel free to chatgpt it more closely to your scenario, but I think a single sentence is probably the simplest thing you need here.
Your boundaries are totally reasonable.