Make use of TeX and Friends source code for handling PDF symbols, then it is much easier to check different implementations. For example, TikZ/PGF package has both PS and PDF implementations of the same graphical objects. So you can see how PDF literals or PS specials come into object stream.
Also it is really not that cryptic but very much laborious, hence many people rely on classical tools to generate PDF instead of handcrafting pdf files from scratch. Here is a nice introduction from a decade ago for you https://blog.idrsolutions.com/2010/09/grow-your-own-pdf-file...
Also it is really not that cryptic but very much laborious, hence many people rely on classical tools to generate PDF instead of handcrafting pdf files from scratch. Here is a nice introduction from a decade ago for you https://blog.idrsolutions.com/2010/09/grow-your-own-pdf-file...