And COM interfaces. They could be clunky in C/C++ but Delphi implemented interfaces quite nicely[1] back in 1999[2].

And being for Windows, Delphi had full access to Win32 API.

[1]: https://docwiki.embarcadero.com/RADStudio/Sydney/en/Using_In...

[2]: https://en.wikipedia.org/wiki/History_of_Delphi_(software)#B...