No. I've just been building with the WASI SDK and running the resulting binary with a small node.js wrapper script. So, I've only tested v8's WASM implementation so far.

Does firefox have a headless mode, a standalone implementation, or some CLI tool I can use to run a WASM binary? Running stuff in the browser is cumbersome.

You can use jsvu to grab command-line shell binaries for spidermonkey (firefox's JS engine), v8, and jsc (safari's JS engine) to toy around with.

I think there should be a headless mode. For exampl e you can run unit tests using the gecko driver (?) without firefox showing up, running it as some process to perform the testing steps and give results.