Hi,
No experience with Mac, but I would assume that it would work there just the same as on Linux. The command I've been using to build is "./gradlew nativeImage" in the root directory of substrait-java, which should generate a binary at isthmus/build/graal/isthmus.
AFAIK there is no documentation yet; it also took me a while to figure that command out. I'd write it, but I have never used gradle or graal beyond building and running Isthmus, and haven't written Java in over a decade. Probably better if someone who knows what they're doing does it :)
Regards,
Jeroen
PS: gmail threw this in my spam folder! You'd think using a Google-based mailinglist wouldn't cause a Google-based inbox to mark a legitimate email as spam, but here we are.