There was a time (around Blender 2.70) when we did provide Blender packages and it did compile (of course, since all our software is built from source) but then llvm dropped JIT around version 3.5 and it became incompatible with OpenShadingLanguage.

We made a choice that we'd rather forge ahead with modern LLVM and Clang (for Rust, Clang-GCC and Julia) than hang back to support Blender. Given our very limited resources, this was still probably the right decision, however, we might have made a choice to create a special llvm35 package at that point, but we had no idea that OpenShadingLanguage would take so long to adapt to MCJIT, which the still haven't done to this day, as far as I know.

The important point here is that MSYS2 is a very open-source, limited resources project. We aren't experts in all packages, so if you are knowledgeable about llvm, OpenShadingLanguage and Blender and are interested to do so, then please help out.

For Blender, getting CUDA support into MSYS2 is probably high up on the priority list too.