You can't release Firefox for an iDevice either as Apple does not allow native code that you need for Gecko so they are about equal in ability to run system apps front.
Chromebooks also run Android apps so in the near future there will be a lot more flexibility in what kinds of either web apps or Android apps you can develop. Firefox already runs on Android and presumably will be available for Chrome OS within this year.
Apple doesn't allow third-party interpreters/compilers if they can run code from untrusted sources (Codea and some Python environments get around it by only running locally written code).
Chromebooks also run Android apps so in the near future there will be a lot more flexibility in what kinds of either web apps or Android apps you can develop. Firefox already runs on Android and presumably will be available for Chrome OS within this year.