Receive Extension Transactions for All Extensions on your own account
Extensions themselves can sign up for webhooks for transactions, but those bit exchanges are completely invisible to the broadcaster. They can't make alerts, or estimate revenue, etc. I would love an event for any transaction make on any extension for the authorized broadcaster.
<https://dev.twitch.tv/docs/eventsub/eventsub-subscription-types#extensionbits_transactioncreate> can just be extended to allow a condition of `broadcaster_user_id` if you already have the `bits:read` scope. So you can do custom alerts for ANY extension on someone's channel, so they broadcaster can thank users on extensions for transactions that aren't always obvious.