You can look at using Wix Fetch or Wix HTTP Functions.
You can see an example of exposing a site here.
Finally, if any payment provider has a npm (nodeJS) that you can use instead, then have a look at Wix Package Manager and see if Wix have allowed it.
Wishlist Page is the new official platform for requesting new features. You can vote, comment, and track the status of the requested features (requests from this page will be migrated to the new Wishlist soon).