Hello,
I have gone through your requirements, you want to add additional feature in your existing android wallpaper app.
I have read all points and no query on it, I am ready to do it.
I just have 1 query now, who will done backend side work? like changes in API.
I have a vast experience in android development so it will be easy for me to understand your code and quickly finish stuff.
Contact me, waiting for your reply.
Let me tell you about myself, I have worked on more than 50 android applications in five years of my professional career.
I have expertise in android development, full knowledge of Android life cycle - Material design - REST api - Sqlite database - Payment integration - Third party library integration - Background services - Firebase.
One more thing I am full time freelancer so will always available for support and communication.
Let me know if you are interested, I am ready to discuss everything before you award me this task.
Thanks,
Hardip