>>42830251I was thinking that it would be like a Grimgar-esque isekai where the world is a lot tougher and grittier. Sure, they know anime and video games, but has any of that taught them the right way to stab a Kobold before it smashes your skull in? Plus they wouldn't know how to actually act out their vtuber selves: Shion would struggle to actually use magic, Gura would trip over herself using a trident, Pekora would... I dunno, chuck her hair carrots at a slime enemy?
Your idea is interesting too, though! It can focus on both you guiding the chuuba and also the chuuba herself coming to grips with her new form. From entertaining an audience over the stream to having to fight for her life in an unfamiliar world.
You can also have ALL of them get /become'd/ and isekai'd as their chuuba selves, and they'll either have get their shit together or get torn apart 