You wont get a definitive answer until you make an extension and put it through the review process, as the review team need to see your exact usage.
My guess would be though that your idea would not pass extension review., as they are often quite strict when it comes to anything that involves bits.
It may be something that would need looking over by Twitch Legal (and I would HIGHLY recommend you consulting your own legal advisors as different countries have different sweepstakes laws, and you need to comply with all of them where you plan to allow your extension to operate).