That's how we've approached the apps I've been involved in. Your Flux or Relay stores and non component modules can be shared. This isn't a hard and fast rule,

That's how we've approached the apps I've been involved in. Your Flux or Relay stores and non component modules can be shared. This isn't a hard and fast rule, just an acknowledgment that different platforms have different constraints and conventions. If you try and share all your code then you'll end up designing for the lowest common denominator, and your app will feel out of place.