So the volumes are stored in RAM, and updated by the GPU? (The last bit about the pointers and whatnot has my scratching my head.)
No need to worry about the pointer thing if the programming language you are using doesn't have them. I'm a C++ programmer, so that's why I mentioned pointer.
Yes, the volumes are stored in an array in (CPU) RAM and are modified by the CPU during volume generation, block add, remove, etc. After the volumes are modified by the CPU, updates are sent to GPU RAM via Vulkan graphics API buffers. (There will be some compute shader updating going on later, but right now it's all done CPU side.)