As I said, you will need to dlsym anything that you may use later.

However, when I did this:

CV* (*Perl_newXS)(pTHX_ const char *name, XSUBADDR_t subaddr, const ch
+ar *filename);

....
Perl_newXS = (CV* (*)(pTHX_ const char *name, XSUBADDR_t subaddr, cons
+t char *filename) )dlsym(handle, "Perl_newXS");
[download]

I got

 error: ‘Perl_newXS’ redeclared as different kind of symbol
/usr/lib64/perl5/CORE/proto.h:2517:19: note: previous declaration of ‘
+Perl_newXS’ was here
 2517 | PERL_CALLCONV CV* Perl_newXS(pTHX_ const char *name, XSUBADDR_
+t subaddr, const char *filename);
[download]

So, that's a neat trick you have there! (though I would make imp static)