Boolean modifier with feathered instead of hard edge

I finished an animation where a mesh is slowly revealed from the bottom up using a boolean difference modifier. The target mesh acting on the modified mesh is a simple cylinder that initially encloses the modified mesh, then rises upward to reveal it as the modified mesh exits from the lower end of the cylinder. This works just fine, except that I would like there to be a gradient/fade effect at the transition point instead of a hard edge.

Since this object has a uniform surface material, I can achieve the desired effect using a texture with a gradient that fades to transparent (then animating the texture coordinates), but this only acts on the surface of the mesh instead of its entire volume like the boolean modifier does.

Is this end result possible in Blender? Thanks in advance for any advice!

The easiest maybe just hide the hard edge with a moving particle emitter and/or a light emitting ring moving up too.