My testing has been w/ a Lunar Lake Core 258V chip (Xe2 - Arc 140V) on Arch Linux. It sounds like you've tried a lot of things already, but case it helps, my notes for installing llama.cpp and PyTorch: https://llm-tracker.info/howto/Intel-GPUs

I have some benchmarks as well, and the IPEX-LLM backend performed a fair bit better than the SYCL llama.cpp backend for me (almost +50% pp512 and almost 2X tg128) so worth getting it working if you plan on using llama.cpp much on an Intel system. SYCL still performs significantly better than Vulkan and CPU backends, though.

As an end-user, I agree that it'd be way better if they could just contribute upstream somehow (whether to the SYCL backend, or if not possible, to a dependency-minized IPEX backend). the IPEX backend is one of the more maintained parts of IPEX-LLM, btw. I found a lot of stuff in that repo that depend on versions of oneKit that aren't even downloadable on Intel's site. I couldn't help but smirk when I heard someone say "Intel has their software nailed down."