This isn’t a PolicyPak limitation; you could theoretically have unlimited PolicyPak policies (entries) within one Group Policy Object.
That being said, the only major concern would be the overall size of the “registry.pol” file WITIHIN the Group Policy Object itself (found at following location:
“C:\Windows\Sysvol\sysvol\Policies\<GUID>\user or computer”
On Windows XP and Windows 7, the maximum size permitted by Microsoft is 5MB, and usually, it takes almost 10-15 Paks entries to reach 5MB.
On Windows 8 and later, the max size is 100MB per Group Policy Object, meaning you can have a lot more entries if you wanted within one Group Policy Object without issue (provided your target machines are Windows 8 and later).