I've been running LLM models on my Radeon 7600 XT 16GB for past 2-3 months without issues (Windows 11). I've been using llama.cpp only. The only thing from AMD I installed (apart from latest Radeon drivers) is the "AMD HIP SDK" (very straight forward installer). After unzipping (the zip from GitHub releases page must contain hip-radeon in the name) all I do is this:

llama-server.exe -ngl 99 -m Qwen3-14B-Q6_K.gguf

And then connect to llamacpp via browser to localhost:8080 for the WebUI (its basic but does the job, screenshots can be found on Google). You can connect more advanced interfaces to it because llama.cpp actually has OpenAI-compatible API.

Yes - I'm running a LM Studio on windows on a 6800xt, and everything works more-or-less out of the box using always using Vulkan llama.cpp on the gpu I believe.

There's also ROCm. That's not working for me in LM Studio at the moment. I used that early last year to get some LLMs and stable diffusion running. As far as I can tell, it was faster before, but Vulkan implementations have caught up or something - so much the mucking about isn't often worth it. I believe ROCm is hit or miss for a lot of people, especially on windows.

IDK about "efficiently" but we've been able to run llms locally with AMD for 1.5-2 years now

llama.cpp and lmstudio have a Vulkan backend which is pretty fast. I'm using it to run models on a Strix Halo laptop and it works pretty well.