We’ve just implemented Intel Open Image Denoise for lightmap GI denoising in Dev-Rendering. Denoising in preview is not supported as the latency is very high. However you should be able to get way less noise in baked lightmaps. Still, to get good quality with this brute force renderer you’ll need very high sample counts (16k). The denoiser may be able to reduce that to 512 - 1k though.