The largest example of this is probably CLANG. https://en.wikipedia.org/wiki/Clang
DRM is fundamentally incompatible with open source licences like the GPL. You almost certainly cannot distribute other people's open source code with DRM. Other people wrote code and developed software that they'll give you the right to copy it under copyright law if you follow their rules. The AppStore does not meet those rules.
This is easy when you're the sole developer of an application, but almost impossible for existing GPL projects where you must track down all contributors and convince them to assign copyright to you.
The reason Apple does not allow GPL applications on the App Store is because it would be in violation of the GPL license for them to be there. The way the App Store model works requires static linking of both Apple and 3rd party libraries, which, amongst other things, is a violation of the GPL.