What does GPU assembly look like?
You're tilting at windmills trying to learn "GPU assembly", and it's due to the differences between how CPUs and GPUs are made and sold.

Each CPU has what's called an instruction set architecture, for example x86 or ARMv8. The instruction set is the interface between the user of the CPU (i.e. the programmer) and the chip. The chip designer publishes the details of the instruction set so that compiler vendors can write compilers to target that instruction set. Any CPU that uses that instruction set can run the same binaries. (Extensions like SSE make that slightly untrue, but they only add new instructions: they don't change the structure of the binary.) When the vendor creates a new processor family, it could have completely different micro-architecture internally, but the same instruction set.

GPUs are not like this at all. For best efficiency, the instruction set is usually closely tied to the micro-architecture of the CPU. That means each new family of GPUs has a new instruction set. GPUs can't run binaries made for different GPUs. For this reason, the instruction set usually isn't published: instead, your interface to the GPU is the driver published by the vendor for each graphics API (OpenGL, Vulkan, DirectX, &amp;c.). This is why the graphics APIs have functions to take the source code of a shader and run it: the compiled shader only runs on the same model or family of GPU it was compiled for.

The closest you get to GPU assembly language is SPIR-V. This is an industry-standard intermediate representation, which GPU vendors are starting to support. It's like a GPU equivalent of LLVM's intermediate representation. It allows you to do the parsing and source optimization parts of compilation up-front to get a SPIR-V file, and then the GPU driver only needs to compile that to the GPU's instruction set at load time.