I like the idea, I definitely think there is potential in apps helping with teaching music, of course this isn't anything new, but the direct feedback possibilities have improved a lot with recent ML / AI advancements. As others said, singing is so much more than just hitting the right notes of course, so understanding the scope of the tool is important. But still, it's a neat idea. It's awesome that AI coding tools have made it so much easier to work out these ideas... but also tricky because everyone seems to make their own now, and it's not even per se the best ones that survive.

I've thought about these kinds of apps a lot recently, and am also working on some (not for singing though), I have a programming background (and a PhD in Machine Learning) but still I am impressed by what Claude Code can do so I'm hardly writing a single line of code myself any more. Asking for the right things is still important of course.