Apology appreciated, but unnecessary.

I don't want to derail a useful tool. It's worth going a bit beyond "hope" as a strategy, however, and thinking about if (how) this might be exploited.

I doubt anyone will be mining crypto in your sandbox. But perhaps you should think about detection; might it be possible to mask a malicious crate with a second that attempts to detect sandboxed compilation, for instance?

In any case, I think this still looks exceedingly interesting in the typical case, which is of detecting the impact of bugs from non-malicious actors.