Speed for development in Flutter Vs Native

We are a startup trying to understand what an app that is a eCommerce store with some minor AR stuff should take to develop on Native vs Flutter.

Is there anyone who can give a qualitifed answer on this who has done it on both platforms?

Developer reasoning:

  1. Native is taking ca 371 hours on both iOS and Android
  2. Flutter will take longer time since it is a lot of special coding and fixes due to errors it is creating. Due to this it will take 70 hours more to do it in Flutter than in native (Swift and Kotlin) for the same app.

If there are any other problems we are idle ears.