Can we build a Payroll interface by setting up RESTAPI in Payroll vendor's system instead of HCM?

Summary:

We have a request to implement a Payroll interface with a vendor that can only connect to us via RESTAPI configuration in his application. They provided us their system API documentation showing us how to configure the RESTAPI on their web application. This is not the model we use to work today and we are trying to understand if that's the right way to go with HCM Cloud.

Content (required):

Today, our exiting Payroll interfaces uses HCM Extracts to generate files that are, in its majority, send via SFTP to the vendor.

Version (include the version you are using, if applicable):