Hello Dear,
I'm easy to talk and i have a large experience with SAP B1 Development.
Your project is very interesting i'd be happy to help you with its, I'm a Flutter Develop this way is better, because you can use the same App to Android and IOS.
I already have some apps working with SAP B1.
Let's discuss more about your project.
Best Regards,
Ronilson Possidonio.