WRKOUTQ *PRINT will give a detailed list when you provide a specific queue name.
Or a summary list when you wildcard the queue or use *ALL
Then CPYSPLF to a flat file and substring to get your data.
Spool files information is kept in *outq objects. With the ability to associate outqs with printers (or not) and to move outqs from printer to printer leads me to believe there is no one repository for all spool files. There may be one place where all outqs are listed.
There are several files in library QSPL with names like Q04079N001, Q04079002, etc. Each member of these files is a spool file. Display one and you will see the SCS control characters interspersed with the data. Part of the content of an *outq object has to be pointers to these members. Best I can tell there is no relationship between a file and a printer, or a queue.
Why don’t you checkout the QUSLSPLF API. Works great nd fast. Up to some 123000 spoolfiles because of limitations with User Spaces. Another set of API’s that work with lists of objects overcome this limitation.