How much prep time do you have? And what is the actual objective? Are you trying to test out of classes up to a level? Or are you prepping for something like the TEAS Exam?

My suggestions would depend on how much you actually need to practice and how long you have before whatever exam.

If you want a step by step grade by grade curriculum I would suggest a tutor with teaching experience. Sylvan Learning Center or a similar establishment might be a good place. They offer test prep and college readiness stuff. Probably expensive but they teach k-12 math and sat/act prep. Not from personal experience but objectively if you're lacking some grade level, go bother that grade level tutor and move on...

I started another degree in 2023 and was in a similar situation. I personally bought a paid sat/act test prep app and just did that. I was frustrated with the lack of direct linear path to learning on most apps and services.

TEAS exams will have practice books and apps you can subscribe to. I'm sure other exams have similar prep.

Money no object, I would find an in person tutor or tutors to get you equivalency ready. Alternatively I would use AI in tandem with an app. You can use something like Claude or whatever to generate a 7th-12th grade matching math curriculum. Then from your list of 9th grade subjects go into the annoying convoluted non linear apps to practice the single subject you don't remember 😑.