AGK Libraries on GithubHave a read of the
teir 2 sticky at the top of the classic forum. You can recompile the AppGameKit classic libraries then compile the players on any platform that you have the hardware to compile on. (Win,linux,mac, ios,android, Pi)
There is no source code download for AppGameKit Studio - just classic...so no tinkering with the vulcan renderer
I've probably trivialised the difficulty of this. Its no easy task to set everything up and then make changes to a very large library. You need to know C/C++ and be a fairly capable programmer to actually be able to make any meaningful or useful changes. And while it sounds easy to make minor changes - you have to make sure they are as platform independant as possible (completely cross platform) and then test on any platform. Its not simple and takes time to find out how things are done in the first place.