Hey,
see may comment under the issue. This addition looks like a plausible feature to implement and it seems that it can work also on Windows.
I like the second proposal, to make it a separate function ffi:load-main-program, because this is different from loading libraries.
If someone steps in and implements it, it is important to add regression test to src/tests/normal-tests/embedding.lsp (so we can check if it works on other platforms / architectures by simply issueing make check) and adding information about this interface to the new documentation to src/doc/new-doc/extensions/ffi_dffi.txi . Also implementation should cover also Windows. Otherwise I'm putting it in my backlog, but I probably won't tackle it very soon.
Best regards, Daniel