I want to experiment with graphics programming without using APIs like Vulkan and write GPU code at the lowest level possible. I believe a lot of complexity can

I want to experiment with graphics programming without using APIs like Vulkan and write GPU code at the lowest level possible. I believe a lot of complexity can be shaved off with added advantage of a custom rendering toolchain. I can do native voxel primitives and ideas from Ken Silverman's old voxel engine, all implemented in the GPU. The only problem will be cross platform support. I would really love a low cost board with open GPUs for that. Custom software renderers are the future I am looking forward to. Its the holy grail to ultimate developer freedom, without the complexity and verbosity of current day situation. Cross platform will need work from hardware manufacturers though!