My first advice: listen to Morrus. He's been doing this for a while so he knows what he's doing.
My second advice: The relevant part here is, I think, section 15 of the OGL. This is where you list both your own book, as well as any source you're incorporating OGC from. Note that you need to include the full section 15 of any source you use. For example, let's say I want to publish a book that includes the Beer domain from Midgard Heroes Handbook. If I do, I have to include all of this in section 15 in my own book:
And then I add my own product, something like:
Staffan's Big Adventure © 2021 something something.
And the Beer domain doesn't really have anything to do with "Deep Magic: Elven High Magic", but I still need to include that in my section 15, because it's listed in the source I took the Beer domain from.
Also, did you notice what
isn't on the list above? D&D. D&D is
not open content. Wizards of the Coast has released a System Reference Document which
is open content, and which mirrors much of what is in the core books, but they are not the same. If you want to publish stuff, you would do well to leave your books somewhere out of reach and rely on what's in the SRD. You don't want to accidentally include a wizard who can cast
Bigby's hand and get a nastygram from Hasbro's lawyers.