You could create your own adapter based using Embedded Python. Here you can find an example of connection with Python and here an example of a similar adapter that I created for connection with Firebase.

I'm not very sure that you should extend EnsLib.REST.Service to define a REST service with URLMap, but anyway, EnsLib.REST.Service is using EnsLib.HTTPInbound.Adapter so you can get the input data from OnProcessInput like this:

Method OnProcessInput(pInput As %GlobalCharacterStream, Output pOutput As %RegisteredObject) As %Status
{
     set authorization = pInput.Attributes("authorization")
...

Here is the doc related: https://docs.intersystems.com/healthconnect20251/csp/docbook/DocBook.UI....