Research: WooPay with deferred intent UPE

[FangedParakeet]

Description

WooPay must be supported within our deferred intent UPE implementation--for more information on the specifics of the shape of this implementation, please see #6291.

However, before we are able to plan and proceed with this implementation, it would be very helpful for us to gather some more knowledge about the existing implementation and what will be required to port this feature over to the deferred intent UPE. Here are a few useful questions that we would like to find answers for.

• How does the existing implementation work?
• Which parts of the existing implementation are readily reusable?
• Which parts of the existing implementation will need to be refactored/extracted?
• Which parts of the new implementation will need to be create newly from scratch?

The result of this research can be a comment explaining findings on this issue, but please be ready to bring your findings with you to our squad meeting next week (June 2nd) to share this knowledge and discuss the ramifications with the rest of our squad as well.

Additional context

#6291

[FangedParakeet]

My thoughts poured out over here -> pbIwZe-1tI-p2

[FangedParakeet]

To summarise my thoughts from my marathon P2 (pbIwZe-1tI-p2), the WooPay integration will likely not require any server-side changes and most of the work will be concentrated on the client-side of the plugin. The most important consideration is that we will need to ensure we are making Stripe API requests on behalf of the platform.

Considering these optimistic revelations, while still allowing for some small amount of development uncertainty, we have decided to bestow #6291 with 3 points of estimated effort.