An app that creates music notations from an audio recording

this is often called “audio to midi" or "Music Transcription". the best ones specialize in an instrument (piano, guitar, voice...).

free/online options :

https://basicpitch.spotify.com/

https://ai-midi.com/

https://samplab.com/audio-to-midi

You will have to convert the midi output to notation in any notation software like Musescore

Thanks, this is also really useful as I will be able to test the conversion accuracy with my ears before attempting to play it.

You can try Sonic Visualier [1] with Chordino plugin from the Vamp Plugin Pack [2]. It won't give you a full notation, but it can estimate chords from the audio recording.

[1] https://sonicvisualiser.org/

[2] https://code.soundsoftware.ac.uk/projects/vamp-plugin-pack

or the Silvet Note Transcription plugin [1]

[1] https://code.soundsoftware.ac.uk/projects/silvet

AudioScore is a professional option. There are a few trial for its older versions available on the Internet. But it is not running on Linux.

https://www.avid.com/products/audioscore-ultimate