Welcome to allnurses!
My hospital-based diploma nursing program (many
years ago) was a complete curriculum with no "prerequisites" (all the courses now considered prerequisites by most programs were built into the program). In our program, the entire freshman class took a year of A&P, a year of organic chem, and a semester of micro simultaneously (plus nursing fundamentals, a year of freshman English, a semester of intro to psych, a semester of intro to sociology, and a semester of nutrition, over the course of the academic year). We took all these courses at a local university (we rode a bus from the hospital three days/week), and they were the same courses the university chemistry, bio, and pre-med majors took, not watered-down "XXX
for nurses" type courses. We weren't offered any other choice, that was the curriculum, take it or leave it, and no one suggested that was a bad idea. It was demanding, but we all survived. In fact, it was "easier" than the subsequent two years of the nursing program.
I'm somewhat suspicious of taking A&P1 and A&P2 simultaneously; A&P2 is usually designed to build on the content covered in A&P 1 (at the university at which I was taking my classes, it was a semester of anatomy followed by a semester of physiology. Hard to do well in physiology if you don't already know the anatomy). Other than that caveat, if you're reasonably intelligent, focused, and motivated, and not also trying to work, I don't see any reason why you wouldn't be able to carry that load and succeed.
When would the ABSN program(s) in which you're interested start? If you're signed up now for classes in fall semester, wouldn't you have at least two semesters to get the prerequisites done? Would you be applying to any nursing programs that would start earlier than next summer? Wouldn't most of them start a year from now?
Best wishes for your journey!