How would I go about developing an app similar to garageband?

I would like to make an app that allows the user to record multiple tracks, apply mixing and mastering tools, and export their file. I can’t find a single thing online about this topic, as audio engineering software appears to be pretty niche. If anyone has any leads please let me know. As an audio engineer, I would use my app and so would others, and I think that would make it a good project to have on my resume.