> The patch adding 'name' and 'path' to the ImportError str/repr 
> was not merged yet.

It's up to whatever code raises an ImportError to determine how the name and path should be included in the error message. In Windows, the DLL name was added to the exception message in 3.8. So I'm closing this issue again, with regard to its final scope. 

With regard to its original scope, the reason for closing is "wont fix". There are no plans to extend the import error of an extension module in Windows to include the missing DLL dependency that caused the import to fail. There are tools such as the "DLL Diagnostics" package on PyPI that implement a proper trace by parsing loader snaps, and at the very least there are tools such as dumpbin.exe (or link.exe /dump) to manually list the direct dependencies of a DLL.