One missing feature is the native code support for JNI.. Currently you have to manually provide JS functions to CheerpJ, and this isn't integrated with CheerpX AFAIK
As part of the next release cycle we plan to release our C/C++ JNI implementation so that 3rd party JNI components can be compiled to dynamically loaded .wasm libraries.
This will be based on Cheerp (our C++ -> WebAssembly compiler).
Integration with CheerpX is another possibility, but we think building the modules from source it's a more realistic solution in the medium term.
CheerpJ uses http byte range requests which reduces the amount of necessary downloads. My full featured Java app downloads < 20 mb with CJ, which is about the same as hitting the front page of NYTimes.com or spending 20 seconds on YouTube.
