What you are describing (facing the network through a launcher over the network) is for sure possible today on mobile, yes. Though you can expect every mobile phone or embedded/IoT device (think of google's chromecast) to have a sparing parter in the network to proxy to SAFE. Neither can you be sure to have that running on the phone itself (due to limitations of background services provided across app boundaries). That is clearly not the way forward.
We are investigating right now how we could change the launcher and app access to the network to provide for these and other use cases. That will very likely mean that the way they interact with the network will different from the current HTTP-Rest approach.
So, while you can for sure do what you are talking about, the question would be: what do you want to Demo? If you want to demo the technical feasability of doing HTTP-Rest, then there is little point as we'll probably drop that for the mobile/embedded use case all together. If you want to proof that it is possible to build nice apps for mobile, which can (generally) interface with SAFE, then by all means: go for it!
We are also experimenting with a cross-builder fork that contains cross-compiled rust-code via FFI, too – not yet documented how to do that though. Which is probably what we'd be doing to port the demo app, should we move forward without a http-based launcher.