Well, anything POSIX or GNU does support the --. I think most golang libraries as well? And if the program does not, you can always pass the files as relative paths (./--help) to work around that.

For sure though, this can get tricky, but I am not really aware of an alternative. :/ Since the calling convention is just an array of strings, there is no generic way to handle this without knowing what program you are calling and how it handles command line. This is not specific to xargs...

Well, I guess FFI would be a way, but it seems like a major PITA to have to figure out how to call a golang function from bash shell just to "call" a program.