I've been listening to Lemon for almost 25 years, and I never get tired of it.
Personally, I find 'A man melts the sand so he can see the world outside' to be brilliant. I mean, that's how glass is made, windows are made of glass, you look out windows to see outside. I think it ties in with the original question.
He turns his money into a light to look for her
Another image of using a resource, here money rather than sand, to be able to see, hear through lighting darkness rather than a window. While the song originates with the story of the home video featuring Bono's mother in a yellow dress, I don't know that's what the whole song is about. Surely the lines about banks and cathedrals and a man makes a car don't directly tie back to the original theme.
I think the entire song, really, is about searching for something 'other' in a world of confusion and, again, using resources, be it money, sand, videotape, etc., to find answers. As 'these are the days where our work ha come asunder ...' we are seeking order in the chaos and a plan in the random.
I think Bono just started riffing off the original idea of looking back through time thanks to the video to find his mother and went from there. His young life was thrown into chaos by his mother's death, and he's been trying to find order and reason since. The idea starts there, but it doesn't end there. The references to cars and banks brings the concept forward to adult life.
She had heaven, and she held on so tight ... I could talk about that one for three hours.