Audiobook android app

I want to add some features on a project from github / transform it from an audio player to an audiobook player.
There are 2 options of doing it so you can take the most the fits your skills and its faster/cheaper to do.

The server im using is ampache: https://github.com/ampache/ampache
Subsonic API: http://www.subsonic.org/pages/api.jsp

1. Option 1: The player can be found @ https://github.com/austinried/subtracks

The project is coded in React Native + TypeScript , exoplayer and uses react-native-track-player (https://github.com/DoubleSymmetry/react-native-track-player) and the main developer is working adding some of the features im asking here

What i need added /changed:

A. Simple stuff:

- Variable playback speed (can be done with setRate , i want the option in the player screen)
- Next track / Last track buttons when player is minimized
- Go forward / backwards for the current track by X seconds (buttons in the player view)
- Sleep timer (stop playing after X amount of time , i want the option in the player screen)
- Keep screen on option.(under settings screen)
- Minor customization to home screen

B. Changes that uses Subsonic Api:

- Continue where you left on different device (Check the server (API: getPlayQueue, savePlayQueue) when you login in the app for where you stopped last time and show an popup asking if you want to start from there, ofc the savePlayQueue should to used to send the info to the server at different states ( paused , left the app , stopped etc..)
- Bookmarks section in a menu with option to delete bookmarks from the list as well of adding bookmarks from the player screen (API: getBookmarks, createBookmark, deleteBookmark).
- Add Genre section to Library screen (API: getGenres )
- Starred section (only for albums) moved in a separate menu (is already implemented)
- Artists / Album description. (API: getAlbumInfo)
- Star rating option (5 star) for albums ( in the player screen and showing it over ablums art, API: setRating ) - optional

C. More advanced stuff:

- Chrome Cast for audio
- Android auto (if possible or supported)
- Subscribe Option (the best option i found so far is https://stripe.com/ , it has react native modules)
- Login Screen (login/register/forgot password ) - the app already has a "Server section" that can be converted to a login screen but it needs some tweaks as it supports multiple servers (and i only need it for my server)
- After you are logged in in the settigs/account screen should have option to Logout , Change Password and few information about your account.
* i need to figure out how i will handle the subscribe option , i havent decided yet, it will need some server side tweaking (i can change roles on my server and set different permissions )

2. Option 2: The player can be found @ https://github.com/popeen/Booksonic-App

This app have all the futures included and its coded in JAVA but doesnt look as good as the first one.

What i need added /changed:

- remove all unnecessary stuff/features (basically i want only the functionality that i just asked for the other app)
- hide some settings and set them a fixed value
- the home screen after you logged in to show something similar to the other app meaning that it should show the album covers in a scroll right fashion for "new added" etc..
- the options from the current home page should be moved to the main menu
- some minimum design changes so it will look more modern
- Subscribe Option (the best option i found so far is https://stripe.com/ )
- Login Screen (login/register/forgot password ) - it already has one but not with the functionality i need.
- Settings / my account screen with minimum options
- some other changes that we can talk on chat.
*something similar so you can try without building the booksonic app you can find @ https://play.google.com/store/apps/details?id=ga.asti.android

When we done i want the app to be almost ready for play store.