In case it can help, you will find here an Azure IoT Device Simulator upgraded to .Net Core 3.x.
The solution allows to simulate a broad part of the Azure IoT Device SDK.
Those capabilities include features like:
The solution runs as a .Net Core console application. It is easily containerizable (you can even find an image ready to use here).
The solution can be used as a developer tool (I guess, this is its primary use) or to build a simulation platform. This could maybe complete the simulation capabilities of Microsoft IoT Central.
A .Net Core 2.x version exists too.
Enjoy your IoT project ;).