On my Big Sur machine, `bash ./hello.com` works the first time, but then it overwrites itself(!) with a Mach-O, so further executions have to be `./hello.com`.
Yup, that matches my experience running the example (I also had to put it in $PATH for the command -v in the header to work). I built program.com myself and it seems to be missing the DOS header for some reason, so it just doesn't execute at all…I'd file a bug, but I have no idea if she is interested in supporting it or if I can provide any useful information besides "it doesn't work".
Glad to hear you're using it! You can ping me on Google Hangouts (jtunney@gmail.com) for help. We also might be able to set up a Slack or IRC channel to iron out these issues. I actually didn't post this thread because I was still working on fixing the long tail of minor bugs. But now that the project has caught everyone's attention, we might be able to fix them sooner!