Actually we could do it, it's basically "just" loading gaia's system app packaged for android web runtime. That would still need quite some work as we don't have yet feature parity on some api support.
That sounds like a cool contributor project that could be mentored.
There is Firefox for Android, you can go to https://marketplace.firefox.com to test most apps. There are some apps that only specify manifests for Firefox OS.
The everything.me launcher may provide some of the look and feel of Firefox OS. http://blog.everything.me/2014/02/06/mozilla-and-everythingm...