At the moment, there is no way to export posted Vendor Invoice lines from the system. We can only export Pending Vendor Invoice lines or Invoice journal lines which is the result we get when using Vendor Invoice lines or Vendor Invoice Journal lines data entities.
An option to either have a data entity of posted Vendor Invoice lines or a report showing Posted Invoice lines (similar as Invoice journal inquiry but on the line level) would save a lot of time for manual line checking for Finance and AP Teams.