Every app needs feedback from its users. It's a very important step in the lean development cycle of creating a good product.

There are multiple ways

Intercom WhatsApp HockeyApp Native & Custom
Native (No build expo possible) JS & Outsourcing all functionality JS & Lots of work
Boilerplate Oneliner Boilerplate Lots of work
Nobody knows intercom Everybody knows
(and has) WhatsApp
Bots WhatsApp Bot is also
possible or push notifications
Everything is possible
Button overlapping in screen Freedom where to put button Total freedom
Complex Simple & Elegant Very complex, Lots of work