@SameerS97  Below  is a GenAI-powered  answers validated against the below references:

"You can configure the SOAP connector to include a digital signature and encryption using a WS-Security profile.

For REST connectors, you would need to write custom logic to create a SOAP envelope and use the pyInvokeRestConnector activity. The SOAP XML can be set as the HTTP POST body and the activity can be triggered. If the REST call needs to be secured by OAuth2, an OAuth2.0 authentication profile can be added to the Connect-REST configuration".

Soap envelope in Connect-Restt

Configuring digital signature and encryption for SOAP connectors

How to implement SOAP connectors when you have a binary encoded license

2-way SSL on Connect-SOAP

WS-Security signing parts (or complete) header.

We are also checking with SME's whether Pega can use the Pega Marketplace offering DocuSign for adding XML signatures as DocuSign provides a REST API for adding an XML signature to a document

SME response:

Digital signatures are not used in our Docusign integration. We use a REST request to POST the document and recipient information to Docusign. The remaining flow occurs between Docusign and the recipient. 

Whether you wish to submit it to a REST or SOAP service will determine this. According to the description you want to send an XML payload to a service, but you didn't specify if the service would be RESTful or SOAPful. 

You can generate the digital signatures using the Api/tools available in the platform using the steps listed in the above documentation for SOAP connector with WS-Security and then create the necessary XML payload that you wish to send to the SOAP service. You can then send the XML payload to their service using SOAP connectors.

Configuring digital signature and encryption for SOAP connectors

As for REST there most likely will be the need for customization and for that you will need to reach out to consultancy.