Would be pretty cool if there was a web tool where people could create a temp map for the streamer and say "hey try this out" (i know it has workshop but its more about engaging viewers) Something more overkill might be something like Polybridge does which is allowing the viewers to "create" the maps or like the solution. The ones already now that are alright are thin/thick trucks, laser trucks and exploding trucks. That can either be a + or a - depending on the map but would still allow you to get through.
Another one could be more interesting modifiers like "Truck Rain" for example. So your viewers could vote for and temporarily give you abilities, this would allow you try out new stuff and at the same time provide something which is neither OP nor Gamebreakingly bad. If i personally had to make a choice for twitch intergration it would be your abilities. In either case i didn't really find any of them satisfying or leave an interesting impact on the game but rather a chore. While on the other hand of the spectrum some of them felt OP like low gravity. Same with earthquake, in almost every map where you need to keep up and jump from one platform to another before trucks move the earthquake would make you unable to get there.
Like double gravity there is never a situation where that is helpful and many situations where maps were PHYSICALLY impossible to complete. Some of them effectively makes maps impossible to play. Let's check it out" and after using i came to the conclusion that its just. I have been looking for some games with twitch intergration to play with my viewers and when i saw it for this game i was like "Cool.