Today, I just found out that one of the world's most popular and most used Installer programs for the Microsoft Windows platform,
Inno Setup is actually made in Delphi! This project has been around since the late 90s.
https://github.com/jrsoftware/issrcDoes not seem to build on Free Pascal/Lazarus according to the README.md file, but it is an example of a production grade ObjectPascal program of which you can analyze the source code for.