There is a framework at
/Applications/Xcode.app/Contents/OtherFrameworks/DevToolsCore.framework
and I was wondering if it’s possible to get the header information somehow?
It’s a framework that theoretically allows to create plugins for XCode.
The header looks like this

and I can’t access the headers as usual with public frameworks. But there has to be a way, because I found some resources online that list the classes, but the class descriptions are not available anymore: https://github.com/phausler/XcodeAPI/blob/gh-pages/Frameworks/DevToolsCore.md
You can use the class-dump utility to extract all Objective-C classes alongside with ivar and methods information.