[Feature] Allow onApprove to be set for hosted buttons

[dougbarrett]

🚀 Feature Proposal

As a developer I would like hook into the completion flow for a checkout experience when using the hosted-buttons component which would allow me to update the UI as needed on the page that is hosting the javascript to render the 'hosted-buttons'.

Motivation

The hosted buttons solution works great for me, but I am unable to hook into the onApprove method that is found in the Buttons component which is preventing me from easily updating the page after we've detected the user has completed the payment flow.

Example

This feature would be used to update the copy on a page dynamically. I've been able to do this successfully with the subscription model on this page: https://cubscoutpack3604.com/ which allowed me to deploy the checkout experience with significantly less code and overhead on my end vs me building out server-side endpoints to handle the order process.

If I were able to do something similar with the hosted-buttons solution, that would be amazing.