It’s sadly a bit more of a proof of concept than a hackable project. The docker build in the readme did work last time I tried, and there is a demo site at https://jprendes.github.io/emception/, but I’ve failed to modify it in the past to do other things

There is a fork at https://github.com/emception/emception that is trying to make it more production ready, but it looks like that may have stalled

I guess the search for compiling C++ on some kind of bytecode continues. Thanks a bunch for the links and details, much appreciated.