I’ve now declared that I want to spend some time in an engineering self-study. I think the very natural next question is: What do you hope to have learned or accomplished by the end? This is the draw of a degree - at the end you have nice little thesis or capstone project you can wrap a bow around and, in return, you get a piece of paper. In my case, the one I got said “B.S.” right on the front but it’s still considered valuable.
Very impressive insight. Need guts to leave a lead position and well paid job! Wish you well in your curiosities.