This is the shortest article on this blog, because the answer is short: publishing to a personal Facebook profile through an API has not been possible since 2018, for anyone.
What changed
Facebook used to offer a permission called publish_actions that let apps post to a person's timeline. It was removed in April 2018, in the round of API changes that followed Cambridge Analytica. Nothing replaced it. The capability is gone.
So when you compare schedulers and none of them support personal profiles, that is not a gap in the market. It is the market working correctly.
What to use instead
A Facebook Page. It is free, it takes two minutes, and it is the only surface Meta lets software publish to. Pages also give you insights, which personal profiles never did.
If your worry is that a Page feels corporate for a personal brand — most musicians, photographers and writers you follow are already posting from Pages. You cannot tell from the outside, and neither can their audience.
If a product does claim to post to personal profiles, ask how. The honest answers are "we remind you" or "we automate a browser session". The second one risks your account, not theirs.