Snapp! (@depthsoftheunknown: <i>!</i>) does not make native android apps. Sounds like an excellent project for someone who understands native android development.
As for themes, we really like the one we have. (Some of us like the flat one, for some reason.) In particular, looking just like Scratch is not one of our goals, especially since they moved to hideous Blockly blocks. Also, in Snap! the visual display isn't just an overlay on some underlying "real" language; the blocks themselves carry their meaning. This means that tinkering with the appearance can easily mess up the evaluation -- and then you ask us to debug your mod, which we don't have time to do.