Does this effort take you closer to the (supposed) goal of running arbitrary X86/ARM Linux binaries as cloud functions, or is that a completely different direction?
At the sandboxing level, it's already possible (you can upload any binary and fork/exec it from one of the supported languages). That's made possible by gVisor, which is the underlying sandbox technology used in GAE and GCF.
As for making that an actual product, we're working on that, too. Sign up for the alpha here:
