I would first speak with the teacher in your child’s school that teaches any of the math or science AP classes for their thoughts. Talk to other parents who have students at other schools that might have the class. See if your student can somehow take that class there. This might actually be more possible if the class is being taught remotely.
Your student does not have to have academic credit at the high school to take the test. Let’s chat to see if we can find a number of students that I could teach the subject to—there is always a solution!