Android 10 MP3 player

I have a cheap Chinese no name brand car audio head unit. I do not like the mp3 player that is in it. Especially the way the shuffle works and it does not play playlists. I am having problems trying to make one for myself. I want it developed in Visual Studio 2019 or Visual Studio 2017 and I want the full source code to make a few changes to it myself. I want the program to be able to find music files anywhere on the device itself and or an external drive. The head unit has 2 USB connectors on it. The current music player on the head unit does find all the music on a thumb drive that I plug into the USB connectors. I am not worried about graphics or visualizations, simple buttons are fine. one screen to show what's playing and second screen to show the songs and or playlists. I expect to have the ability to create the APK myself to do the install.