On brand identity, I think it is okay to post on multiple topics from the same channel (or at least to reference them). In your case, especially if you are going with "The Pentographer" that already is a blending of two separate topics in the name.

I plan to post on a lot of different topics, but hopefully mostly somewhat connected under "Retro Edge" themes. That includes hardware, both older and newer, software, programming. Most things I am interested can be loosely connected logically with thematic "content pillars".