Allow viewers to authorize a channelpoints transaction via API
As it stands now, it is not possible to subtract channel points from viewers as there is no endpoint for it. After looking around online it seems to be because there could be malicious uses for the endpoint, where an application could drain/burn channel points from viewers.
To circumvent this, give us a way to ask the viewer to accept a "transaction". This could be a small popup above the chat with the:
Application name,
Amount of points,
A small description of the transaction.
The application would get a result back whether or not the viewer authorized the transaction.
If anything goes wrong at any time the broadcaster or moderators could refund the channel points.

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At this time, Twitch is purposefully only allowing Channel Points redemptions in the chat UI on Twitch.tv for a consistent viewer experience in addition to any safety concerns. While this could potentially change in the future, I'm going to respectfully close this suggestion for now to confirm this is not actively being investigated. Although declined, please feel free to add any further context for future consideration.