Half walkable nodes in grid graph?

Is there anyway to make the 8 connections grid graph have nodes that are only walkable in half of their area?

Screen Shot 2020-11-10 at 19.46.17

So I have this scenario where the astronaut attempts to walk and because it is the player character and I want the movement to be smooth Im not using pathfinding, but I want to use the walkability of the nodes instead of collisions. So Im checking if the GetNearest(transform.position + movement).node node is walkable and then saying okay you can walk, else you can’t

But in the case of the picture, it just stops walking and I want a diagonal movement, for that I would need a diagonal kind of grid, or you can imagine, half of those squares being walkable and the rest unwalkable

I really hope I made myself clear,
thanks in advance and I appreciate any help with this!