I've tried it, but the resulted built size is huge. How could a Hello World application (built for android) took 15 minutes to build, and about 60MB in size ??
Why not those measurement been told in the main site to tell other to try and use ?
Others have noted that this should not happen, but just to comment on the specifics; the size of a plain APK like a Hello World should be just 6-7MB. Anything else is files in the project path that haven't been excluded (e.g. big images in the project directory) or dependencies that the python-for-android tools have been instructed to include. I don't know what went wrong for you, but that size is highly atypical, and if you're ever interested we can help debug it.
It's possible to reduce the size further, one of our devs has recently been experimenting about this in particular and I think has got down to 4MB without too much difficulty. The problem is that reducing it much further starts to mean being more careful about blacklisting stuff like modules in the python standard library, which can be hard to do automatically without breaking dependencies. It's highligted some potential optimisations in kivy's internals though, so maybe we can make it easier to leave out some non-essential kivy components.
Just to be clear about the build time thing, compiling python + project dependencies may take a few minutes (e.g. your 15 minute figure), but subsequent builds don't need to repeat this and will take just a few seconds.
The actual apk can be as small as 5-6mb, but yes it's too big. Ideally common files to all Kivy applications (the python runtime and libraries) would only exist once, but that's a problem people can't quite agree how to solve. https://github.com/kivy/python-for-android/issues/202
I'm pretty sure apps can have dependencies, so that looks like the best solution. Yes, users will be annoyed, but I think it's still better than various other "hacks".
QT has tried that on Android and it's an exceedingly poor solution. Almost no user will click to download additional files -- they've been (rightfully) conditioned to view this as a suspicious technique.
As long as you blacklist unneeded libraries on Kivy, you can get the size down to 5 - 10 MB. I personally don't believe this download size is such a problem for users (many native Java apps are upwards of 5 MB).
What is a problem is the start-up time and battery usage, both much harder problems to address. Because they require the Python interpreter, Kivy apps take significantly longer to start-up, and use significantly more battery power than Java apps. I have some hope that Micropython may eventually offer a solution to this for Python on Android, although porting Kivy to Micropython will be a major task.
I think startup time has good for very annoying, with android devices of 3 years go, to nearly forgettable, with more modern, high-end devices. I've witnessed nearly instant startups, with devices as the Note 2, not saying it's a solved problem, the cpu speed and even more the read/write speed of the internal storage will have a lot of impact especially on the first start (unpacking python and deps).
For battery usage, i'd love to see data for this, i think drain will come from the amount of action you put in your interface, as well as background processing you'll do, kivy itself, being opengl and cautious about what to update when changes happen, shouldn't add a lot of overhead on this.
I don't think porting to micropython is considered an option, usually, when we want more efficient code, the solution is to do less python, more C, we have a nice integration with Cython, and don't hesitate to go with it as soon as needed.
