Supposing I got that correctly, 3DGS currently renders each group of a model in a seperate pass. That said, I thought probably you could make A6 render the geometrical edges of a group with decreasing opacity (from in- to outside), giving it a smooth-edge effect? This would allow for automated texture blending since two groups with different textures and the suggested "fadeout" effect on their edges would then more or less blend into each other.
As you might have noticed, I don't really know much about those D3D internals, but nevertheless I thought I could as well at least share my idea. Any thoughts, anyone?