Thanks!
Yes we do have plans to add support for low power microcontrollers.
We plan to port the sandbox (which is python itself) to microprocessors for which an implementation of the MicroPython framework exists. For example the WiPy board, which ships a cortex M4, or boards with the ESP32. MicroPython can selectively compile functions both at bytecode level and at native ARM level, with native code emitter, so that it will be possible to achieve performance comparable to native code even on microcontrollers.
If you are interested in document conversion using LO and python you can give it a try to https://github.com/xrmx/pylokit which is a python cffi wrapper for the stable api of LibreOfficeKit.
As a jquery.transmit user I'd say that that the major advantage of js vs plain css3 is in terms of lines of code, especially wrt to browser prefixes. Then I really like to have the timing of animation explicit in js code near the usual .animate(), fadeIn(), setTimeout(), etc... instead of having to check two places.