Get user name from user id?

[BarryCarlyon]

@darkmatterbw

Is it possible to get more data about the user from their opaque id

No it’s Opaque.

@darkmatterbw

if necessary their regular id)? I need a user handle / user name.

Yes, if you have identity sharing enabled and the user shares their identity you then have the users Twitch ID, which you can then use against the API

Reference