To understand the exchange of data between Simulink model and App Designer, you can refer to this example that walks you through the workflow of creating a simulation app in App Designer and using Simulink Compiler to deploy it.
You can use From Workspace block in Simulink to use data from MATLAB workspace in Simulink modelling.
In order to initialize the system from Simulink, you can use Initialization Function (InitFcn) callback function.
