I like the idea they have of sound ads
Although if I must suggest something that you may already have in mind, it is that each streamer will do well with one or another type of ads. Someone who is important is his game or what is seen will love the announcements of sounds like the one they are making. But someone whose audio is the important thing, continues to be bothered by the current type of announcements and the sound ones, for these people they will need announcements that cover a part of the screen but do not mute the subject's audio...
The simplest idea is that the subject can decide what ad to put in their entire stream but if they like to make it more complete, they could make the streamer can confugure the ads but create exceptions in certain categories, for example, that can activate the audio ads but when you are in just chatting, advertisements are placed on the screen without obscuring your audio