I’ve never heard of FAU. Looking briefly at their webpage, they are four-year only so that may matter; my college gives both undergrad and graduate degrees. The OP does not seem to be targeting FAU or similar.
Not required for HS graduation is important, and generally the best idea is to make sure anything not needed for graduation is not on the HS transcript, just in case.
Is it really obvious that if a HS has few AP courses, they have to take college courses in order to get into a great college? That is not what I understand. They look at the most rigorous courses available at the HS and compare what the student is taking. And special courses that are not AP like science research can count a lot.
I don’t see any benefit of taking college courses that count for HS graduation over taking honors courses that count for graduation and self-studying for AP exams.
There are also online AP opportunities available through Johns Hopkins.