In fact, given that it is there since version 3, there are compilers available for almost all major programing languages, including managed ones.
While OpenCL is a C world, and almost no one cares about the C++ extensions and even less vendors care about SPIR-V.
Also the community doesn't seem to be bothered that for a long time, the only SYCL implementation was a commercial one from CodePlay, trying to extend their compilers outside the console market.