The only other option would be to use an extension. This has the added benefit that not only would a streamer have to add it to their channel, but the users themselves would have to opt-in to it by sharing their ID with the extension.
An extension means it’s MUCH easier to be compliant with the laws/guidelines compared to using the chatters endpoint which will be getting data on some users who may not wish to be tracked and potentially not even be aware it’s happening, and also easily provides a way for users view the ToS of the extension and know what user data is being collected and also how to request that their user data be removed if requested.