Thanks for your inquiry. Please refer to the below link to test two way authentication using SOAP UI for hello world request.
Once you are successful with that, you can execute PAAI request from SOAP UI in Sandbox.
For PAAI endpoint, sample request , please refer to the below link.
Test data is available to you in your VDP Project --> Test Data tab.
Reg., Python sample code, kindly look into the readme file to correctly substitute the used id, password and certificates from VDP Project dashboard. Please post the sample code here if you still face issues, so we can take a look.
Let me know if you have any further questions.
Thank you !