Well, I don't have "walls" - my maze is sort of 2.5 dimensions - so that complicates things somewhat. I wonder whether there's an algorithm to "lift" a 2d maze with walls into my 2.5d maze, and I think if it's possible it's WFC or model synthesis. I will go try stuff, just haven't gotten around to it yet :)
You do have walls, they're just implicit. There obviously must be a way for someone looking at it to tell which directions they are permitted to move in.
Don't think of it as an image but rather as a graph of the passable tiles. You can render the nodes and vertices in various different ways.