CheerpX is actually fully dynamic. You don't even need to "compile" things manually before. You can just feed binaries to the JS API and the program will run.
Appears to be proprietary based on the look of the website - what's the price range for this?
Our roadmap is to release our Flash solution in 2020, and we are in the process of finalizing the pricing of that. We have not yet defined how other uses (like REPLs) will work. If you have an interesting use case for our tech, drop us a line info@leaningtech.com