This article discusses software internally used by Apple.
Acquiring a copy without Apple's consent is illegal and may result in being scammed.
Not much is known about Alto, also referred to as
AltoMobile in the filesystem. It seems to be an audio testing application from the files on a complete build of Alto. Images 1 and 2 are from @AppleInternalsh on Twitter.
The contents is as follows on an iPhone 6 running Monarch 13A83262c. The application in this device is broken and missing many files, so please keep this in mind.
_CodeSignature Images MesaPatch
AltoMobile Alto-Mobile.plist AltoMobile.png com.apple.hwte.AltoMobile.plist Entitlements.plist Info.plist PkgInfo