I was going to ask about a combo.of both. Perhaps DE for the not as important to you/rigorous classes, and AP online for the others.
We ran into a bit of that years ago with my S16. He ran out of math at age 12 in our small private K-8 school. Public wouldn’t let him attend unless he was full-time. So he took pre-calc/applied calc in our not very good CC. He was one of 2 students in applied Calc. Then he went to our local not very selective and never mentioned on CC uni for calc and on. Fortunately, he had a couple of great profs there. One taught him one on one for a semester since his class didn’t work with his school schedule.
And also fortunate that the private school principal did all of the leg work to make it happen in the beginning. It was a pain when I had to do it in HS since he didn’t fit their cookie cutter financial system. I always had to get an upper level person to override the system.
We also ran into pesky testing issues with the public. Our kids did attend the bottom of the barrel HS. We don’t have many options here. But you have to pass standardized tests for math. But you can’t take the test until you’re enrolled. So S had to take tests for classes he had had in 4th grade and the syllabus had changed - added stats stuff. But since it had just changed, there weren’t any practice tests to be had, and he didn’t know beforehand. Fortunately, he just had to pass but still. Ugh