So when you have inventoried your computers you get data from whats installed. Im not quite sure what you mean by the list includes all third party software, i think you may be confused on where to get that info from. This is copied from a different post that kellytice responded to
You'd need to run an Inventory task against those machines, so you'd need to schedule the inventory at a time where you can 'catch' those machines online.
Once you have inventoried them, you can go into Patch Manager and under reporting -> configuration management reports, you'll find one of the subfolders has a software inventory report.
When you run that report and get some results you can "group by" the Display Name field by dragging the Display Name column header up to the dark gray area right above the column header line. You should then be able to see a breakdown of what software is out there and who has what - and what versions.