Hi.
At this point this information isn't available using PB. In PB 2022 R2, I guess, you will be able to see number of pages in a PDF file. But from what I've heard so far, R2 won't be released before July 2023. In the past I've used itext to get this kind of information. Take a look at the following question in stackoverflow:
c# - Determine number of pages in a PDF file - Stack Overflow
You could create a simple method in a similar way and use it in PB through .NET DLL Importer.
Also, if you have an old version of PDFCreator (1.6.x or 1.7.x) you can also get that information using pdfforge library that is included and documented. You can wrap the functionality you need and use it with .NET DLL Importer. You can also register the library to be used as a COM object and directly use it through PB.
If you decide to use any of those you should read their licenses.
Finally there are many commercial active-x controls that provides you that information. But you will have to pay, and of course those can be expensive.
Andreas.