Currently the list of allowed targets are:

• default
• google_apis
• google_apis_playstore

However, sdkmanager and avdmanager also have images to support emulators for other devices:

• android-wear
• android-wear-cn
• android-tv
• google-tv

Since the specified target is validated, right now there's no easy way to use any of those 4 targets.

A few possible solutions:

• Expand the allowed list to include all 7 currently available targets
• Remove the strict validation for the targets, to guard against new ones
• Some combination of both (check if it is a recognized target, and if not, warn but don't fail)