Problem with visibility markers through walls

I am trying to make markers on the map that are visible to the player.(first screenshot)

But there is a problem. The marker is not visible through the walls. I used a sprite as a texture because it’s handy. But as I understand it, it cannot be configured to see through the walls.(first screenshot)

There is also a problem with materials. To see it, you need to set the blend translucent mode. Mask cannot be used in this mode. And the black background remains. (2nd screenshot)

The question is what to do?
If you know, please explain to dummy.