Are there any 4 year colleges near you? Some of them will allow homeschoolers (or public schoolers) to take classes there just like community colleges will.
Otherwise, I’d sign up for a couple of CC classes even if they’re subpar because grades in those will be useful on a transcript for college even if the classes don’t transfer. I know what you mean about classes being subpar. Ours often are too. My high stat student was still able to take Microbiology and Public Speaking there. Both were worthwhile for applications and for his future.
If there’s any chance of heading pre-med, be wary of pre-reqs at a community college. Many med schools don’t like them. Note too, all grades will count toward med school admissions even if they don’t count at his college. Both of those applied for my guy, but they might not for yours.