Allow the streamer to add a % discount to all or some of the redemption rewards (ie. Hydrate is 1000, but with a 20% discount it becomes 800). Go all out with it and add a "20% OFF" tag on that redemption to make it known. More of a quality of life thing since this can be done by changing the points manually, but seeing a discount and making a big deal about it would get people more excited about it.