Android music app like maple

This projects goal is to create an android music app like maple but with Spotify integration.
If you dont know the maple player you can search for it on the internet: maple.sqr5.com

The focus of this app is customizability.

The desired features:
-everything a basic music player has
-lock screen player with big buttons.
-flie browser for offline music
-supporting as many audio formats as possible
-lots of customizable settings
-a random function that takes all the selected music files, randomly shuffles them and then gives you a playlist that one can listen to from start to finish.
-Appstore setup and integration is required.
-There has to be the possibility to pay for the app and for donations.

Regarding the Spotify part:
Spotify has horrible search and sorting functionality. With this app I want to provide an alternative where a detailed search with multiple parameters is possible. Also a better way to create an save playlists and a possibility to easily listen to the entire discography of an artist.
-optional: cashing of all the listend to Spotify songs

Scope of project:
Creation of app within less than 4 months and after that, long time support with updates as required by Android and adding of new functions.