Comprehensive Book Reader App Development

I'm interested in building a streamlined book reading app. This application should support both iOS and Android platforms and incorporate features that enable offline reading and book purchase/rental. The design should center around a user-friendly interface.

Key Features:
- Support for Offline Reading: The app should allow users to download and read entire books offline without any hassles.
- Book Purchase/Rental: It's crucial for the app to allow users to buy, rent, and importantly download books. The range of books available for purchase or rental should be broad.
- Integration with Payment Systems: It should enable payments through Telebirr and CBE (payments in Ethiopia) and PayPal/mastercard. Therefore, experience with these systems is necessary.
- Sync with onesimuspublisher.com: The app should seamlessly synch up with onesimuspublisher.com, making the user experience more fluid.

Ideal Skills & Experience:
- Strong experience in iOS and Android app development.
- Proven expertise in eBook app development.
- Familiarity with Telebirr and CBE payment systems.
- Experience in developing apps with offline functionality.