During a boost, as it's described now, people can use up to 2,000 channel points. This isn't an issue for viewers with a lot saved up, but more casual viewers might have to choose between other channel point rewards and boosting. To fix this, making it so channel points spent on any reward during a boost contribute to the boost could help. This makes boosts feel less like a waste of channel points, and could make boosts more hectic and fun. However, if a streamer doesn't want this, they could maybe set a limit on the number of redeems that each viewer can do during a boost. Viewers also could directly put their points toward a boost up to the usual 2,000 point cap (which would account for redeems).

I feel like these changes would make contributing toward a boost more worth it for casual viewers, and would not discourage streamers from having fun and interesting point redeems as the current system could.