backend frontend app

i am looking for someone to help me to develop a social app that will invite some people from your network to look at a private data..
i want to make sure that the data is build in blockchain so it doesn't get hacked or changed

there should be algorithm system as well in the app
sms + whatsapp connection as well should be implemented

Frontend flutter + web
(Mobile app) iOS android

Registration
Invitie friends using sms api + whatsapp
Writing - posting video or image - will using blockchain
Secure encryption
Proof of death concept need explanation

Paypal payment (monthly or once)