Question: Is there an app that allows me to practice music at my own pace and in any key?

If you want an app where you can practice music at your own tempo and in any key, Moises is a great option. This AI tool has a lot of features, including a smart metronome, audio speed-shifting, pitch-shifting and AI key detection. It also can detect chords in real time and separate instruments, so drummers, singers, bassists, guitarists and producers can use it. You can use Moises through its App, Web App and iPad App, so you can use it on whatever device you prefer.

Another option is Fadr, a web-based tool with a variety of AI tools like a key/tempo/chords detector, song splitter and remix generator. Fadr can isolate vocals, bass, drums and melody as audio and MIDI files, and there's a DJ tool for live mixing. It offers a free version with basic tools and a premium subscription for more advanced tools.

If you want to get more interactive with music, Aimi offers a generative music system that lets you control the music generation process in real time. It's got an interactive music player and a studio for creators, so it's a good option if you want to jam with others or be more creative.