Good list of source material?

[Groin]

The list of "other resources " that you can access with the OGS menu is surely another good place to consider (including more choices for a teacher as @bugcat suggestion).

A word on the AI revolution
Because of what AI brought to us (around 2017), mostly new perpectives on the beginning of a game, you need to have some distance with anything on fuseki (opening patterns and theory) and joseki published before AI and that is a lot of resources!
This includes for example the “in the beginning” book of Ishigure you mentioned in the OP (Sadly as i loved that book)

See this topic for more on this

Opening theory after AI

I’m a 20kyu and I was playing a teaching game at a local go club and the player was lamenting the years he spent studying joseki since AI flipped it all upside down. He suggested I spend time studying life and death and a little opening theory. Is there a resource for beginners that teaches opening theory that incorporates the new world since AI has come to the game?