Github app to make http call when pressing button or add label

I’m trying to make or find a github app that triggers a user registered github webhook upon an action by the user.

For now, I’m trying to make it such that the action that trigger looks somewhat like this:

PR line.png

Where “Details” is, if allowed, a button.
Clicking the button would do a call to a github registered webhook by name.

If that is not allowed by github, I’m fine with using a label for the same purpose.

With the label option:
When the label is added and the PR is ready to merge, call a webhook announcing the current status.

Is that feasible?