Thanks for the interest and the question. I think your question can help a lot of users, so I'm linking some useful resources for users who want to develop with OpenCL-C++ and Intel Graphics Compute Runtime for OpenCL Driver (NEO).
At this time, NEO can ingest SPIR-V. Exploring compilation of OpenCL-C++ to SPIR-V may help you. Here are some overview references and examples:
Some spellings for toggles may have been updated between clang version so picking a toolchain to fit your needs may not be so trivial. The Khronos SPIR repo looks like a good place to start to keep it simple.
Hopefully, browsing the above guidance can help you get there. Please let us know how your exploration goes.
Also noteworthy, the ioc64 tool, can compile SPIR-V to both Intel CPU and Intel Graphics Technology (NEO enabled) targets. You may wish to use it to check offline compilation for targets of interest. The ioc64 tool comes with Intel® SDK for OpenCL™ Applications and the Intel® oneAPI beta Data Parallel C++ Base Toolkit.
ioc64 maintainers monitor these forums so if you have SPIR-V usage feedback for Intel platforms this would be a good thread to speak to your experience.
I'd like to add a few additional links to Michael's excellent list above:
Finally, if you are interested in a more complete end-to-end C++ experience, I'd encourage you to take a look at SYCL and Intel oneAPI Data Parallel C++. More information about Data Parallel C++ can be found here: https://software.intel.com/en-us/oneapi/dpc-compiler