Hello,
I have gone through your requirements, you app is facing warning from google play store because you are using SMS permission in your app.
Let me first tell you that I am fully aware of this issue, You have to use alternative 'SMS Retriever API' for read OTP without asking for sms permission.
So, I am confident of implementing this as I already did this for my previous client.
I can do it within a day, waiting for your reply.
Thanks,
Hardip