Huh? > Cosmo could work as a wrapper of windows/mac/linux binary executables and then the cosmo app can decide which one to invoke. It sounds like you misunde

Huh? > Cosmo could work as a wrapper of windows/mac/linux binary executables and then the cosmo app can decide which one to invoke. It sounds like you misunderstand the reason for the project and that you're trying to add another layer of indirection to the thing that is already able to achieve the effect that you you seek to accomplish with that layer of indirection. No need for the indirection, just use the thing directly. If you want to run $APP on platforms X, Y, and Z, then you'd use Cosmopolitan to build the $APP binary as an Actual Portable Executable, and you'd run that executable on any of those platforms.