I have not been able to get the Xcode simulator to work for Big Sur Xcode 13.1. Tapping the app icon on the launch screen of any simulator results in the screen going black and then the home screen reappears with the usual icons. This happens even with the Hello World app that comes with Solar 2D. Nothing appears in the syslog. Drat!
On my older Mac Catalina with Xcode 12.0 I can get the simulators to work - but they are limited to 2019 devices. Not the newer iPhone 12/13 etc.
Are your Xcode simulators working for you?