https://developer.garmin.com/connect-iq/programmers-guide/entry-points/
"The name and launcherIcon attributes must specify a resource ID that is defined in the app resources. If a launcherIcon isn’t specified a default icon will be compiled into the application."
Well, that's not true.
launcherIcon is mandatory and monkeyc won't compile if icon is not set.
ERROR: A launcher icon must be set in the manifest.
com.garmin.connectiq.common.manifest.ManifestException: [102] A launcher icon must be set in the manifest.