Hi! Thanks for your comment! I have answered your question below:

- Are these really 1-to-1 calls? Looks more like a room where many could join? > It is currently only a 1-to-1 call! So you can have a call with only the first follower to join in the room. We are looking to develop 1 to many call functionality soon though!

It's not limited to twitter, is it? I could share it anywhere, right? > You can post the room link on any platforms technically but it is preferred that you post the room link only on twitter!

Thanks,

If you have any questions, please let me know!

Shinji