I’m in the process of cleaning out my “varia” parts bin. It’s a box of neat-looking chips with an id that looks easy to google for datasheets … but most are locked away as you state. There is a fixed barrier for hobbyists around the 100 to 200MHz bus rate area. From there on hardware that’s available for diy projects gets dumbed down or bottlenecked in some critical section. Every once in a full moon you get a glimpse of the product brief for a chip you desoldered from a docsys decoder and see what’s behind the NDA wall. Oh well, here’s to fpgas.