liv-app://camera/set/0 (whatever number in the list you want to switch to)
This command can be Win_R'd to control LIV, or you can use it with a scripting tool like AutoHotkey to either make looping behaviours or just convenient keys for switching
AHK script:
Run, liv-app://camera/set/0
Script to change to camera 2 when you press CTRL+ALT+2:
^!2:: Run liv-app://camera/set/2
More info here: https://docs.liv.tv/liv-app-api/uri-commands-camera