XDP to PDF in OSGI - OutputService

I need to run through a bunch of XDPs (on a filesystem) and convert them to flattened PDFs (for print).

We have AEM Forms (OSGI).

I have been reading here but, I cannot find any reference to OutputService.

https://experienceleague.adobe.com/docs/experience-manager-learn/forms/document-services/output-and-forms-services-article-develop.html?lang=en

I am using the Adobe Archetype for creating custom Servlets, workflow components, etc.  I also have the the client sdk in my pom:

 <artifactId>aemfd-client-sdk</artifactId>
<groupId>com.adobe.aemfd</groupId>

Is there a quick tutorial that will show me how to use the OutputService to take an XDP and generate a PDF?

Thanks,