As far as I could notice, none of the typical settings used for CPU lightmass actually affect the GPU lightmass. Even the number of indirect and skylight bounces (which you needed to crank up for the community baker) have no effect, nor does lighting quality (preview, medium, high, production). All of the settings that pertain to the official GPU Lightmass are found in its unique panel.
Unless you use the irradiance caching (which is the old CPU method for calculating GI, which might get you similar results to the CPU baker but is generally lower quality), the only setting you can really change is the GI samples. Depending on the amount of noise you’re comfortable with, you’ll have to crank this number fairly high to get good results, something like 16 000 or 32 000 samples might be enough to get you a relatively noise-free bake. You can also turn off the denoiser, but you’ll be baking for literal years if you do as this version of GPU lightmass takes a lot longer to resolve than the community one.