That said, even if the tool doesn't help for the musical earing directly, it can still help to correct the position of your fingers, and that's very important for muscle memory. So instead of training for hours on the wrong finger position because I don't have a musical ear, I can correct myself and properly train my muscle memory correctly.

Well, you're very lucky to have a relative pitch, I think you can still train for it as an adult, but it may require more time and still might not be possible for everyone. Don't take my word for it thought, I don't recall any solid research on the subject.