How can I list all instantiated objects in all application, using FASTMM4 or default memory manager?
You could probably do this with FastMM4, but it would be a complicated. Try examining the code for the procedure ScanForMemoryLeaks to see how it's done.
This routine checks all assigned heap memory against the list of expected memory leaks and reports everything that shows up, including a count and the object class name if it finds objects. What you want to do is check all assigned heap memory and report the count and object class name of all objects you find, so it's a really similar task. Just omit the registered pointer list check and filter out everything that's not an object.