Hi Marek,
Thank you for your interest in Syncfusion Products.
We can able to convert XPS to PDF/A document.
Please use the below code snippet:
XPSToPdfConverter
converter = new XPSToPdfConverter();
PdfDocument
document = new PdfDocument(PdfConformanceLevel.Pdf_A1B);
document= converter.Convert("Input.xps");
document.Save("Sample.pdf");
document.Close(true);
Please let us know if you have any concern.
Thanks,
Karthikeyan.C