[againandagain]

Android uses a Java-based VM. iOS does not. Is that correct?

Can you boot your own OS (sans Java VM) on an Android device? How easy is that to do?

[css771]

The Nexus devices are generally the most open of all Android devices. Consequently, there's a Firefox OS port, in alpha right now, for the Galaxy Nexus. http://forum.xda-developers.com/showthread.php?t=1805282

Many Android phones can also run various other distros using chroot.