The docs say you can listen: Extensions Reference | Twitch Developers
Non-extensions PubSub topics also are supported with this function; for example:
channel-bits-events-v1.
I have not tested it myself, the example event of “channel-bits-events-v1.” you are supposed to provide an oauth/scope according to the pubsub docs, but there’s no way to provide an oauth/scope under listen. So perhaps calls to listen in extensions bypass the need for the auth here, as the JWT/Twitch listener handles that.
But a given JWT/listen combo has a specific channelID in the decoded payload anyway.