I'm trying to implement a plugin for KDE which would allow you to add hotkeys on double pressing keys,
for example double caps lock key would trigger home or end, etc.
I've been searching for a while now but couldn't find any resources regarding this topic.
Could you please give me some guidance?
Thank you

Handling global hotkeys is done with kglobalaccel. To set it up you could use the guide on https://community.kde.org/Get_Involved/development.