In the video, Wolfram Video Archive: Integration with Other Software and Hardware Tools Leonardo explained two ways to interact with external models and hardware. There were two possibilities: simulation executable and FMU. Currently, WSM 12.0 only presents the possibility of FMUs.
Can one still generate simulation executables?
Yes, you can still generate simulation executables. You will find this option after simulating the model then selecting File → Export → Simulation Executable in Simulation Center.