https://github.com/mystor/git-revise is great for just this. Of course there's also `git commit --fixup=<commit>` and `git rebase --autosquash` if you don't want to install extra software. But the ergonomics of `git revise` are better.

I've also tried git-absorb before. It was buggy at least back then. Uninstalled when it crashed and lost my changes, and even reflog didn't help.