I’m not sure, but I would be surprised if there was, especially for any sort of modern equipment. Networking hardware is really just a standard computer with a lot of specialized SoC chips specific to networking routines. So your generic home wireless router is an ARM chip, some ram, some storage, and then a wireless SoC chips, for example. Most of your enterprise type switches are basically the same Intel or AMD CPUs you’d find in a server with a ton of specialized single-purpose chips augments to offload specific jobs really fast.
So if there was a very basic beginner course to building networking hardware like, it would probably be using the concepts that 80’s hardware may have used I’d guess. Maybe try looking for someone building a modem or NIC from scratch?