Sounds a lot like my extension, it was created for artists then expanded for gaming streamers: https://dashboard.twitch.tv/extensions/455ecd6oits6646mh2vakb6ootnww4
But, there is some limitations to your idea, you can’t sell things with an extension. You can only provide a “digital experience”, so selling a painting and sending it is not allowed with Bits. And we are not allowed to have a payment system on extensions.