Alpha blended depth masking of sprites in the shape of the sprite, not the internal mesh?

I have been trying this for a week and cant find a way for it to work fast on mobile (without using discard, clip or alpha test). Is there another way? The first shader - Depth mask with alpha blending uses clip. This is the result I want, but without the clip instruction. The second shader - Uses grabpass to achieve the same effect, I am hoping to get it working with light.