I think the macOS console app is a bit overkill to watch the console output of an attached iOS device. So how to get the same data to show up in your Terminal? Thats quite easy.
First install the Apple Configurator app from the Appstore (https://apps.apple.com/nl/app/apple-configurator/id1037126344?l=en&mt=12).
Now run this command and your iOS console messages should start showing:
1 cfgutil syslog
One of the cool thing is that you can now filter with grep like this:
1 cfgutil syslog | grep "DEBUG"