Executable binaries are memory mapped into memory. So the pages are lazily loaded. So in theory you could study how many of the pages (4 KB each) of the binary

Executable binaries are memory mapped into memory. So the pages are lazily loaded. So in theory you could study how many of the pages (4 KB each) of the binary were actually loaded to get a rough idea. Obviously not very precise since it has a 4 KB granularity.