making a 2d maze game

Hello i am trying to build a 2d maze game. It should be level-based so if you complete level 1 you must move to level 2. I made my own level in photoshop, its pixelated and dont have stright walls (pixel art).
Now here the problem comes: its very hard to manually add box collider to every wall, plus i also have different structures like sun etc.
Isnt there a method to do this? like selection etc.?
here are my levels:
level-1 hosted at ImgBB — ImgBB ,
level-2 hosted at ImgBB — ImgBB ,
level-3 hosted at ImgBB — ImgBB ,

Usually, you wouldn’t draw a whole level in photoshop… you would make small “Tiled” sections that are stitched together in the game using a tool of some sort.
Then you only have to add the collisions once per tile.
Go to the asset store and search on something like tile mapper, map tile tool, or something like that.

or look into Unity’s Tilemap

some games that need pixel collision ( worms, lemmings ) might sample the pixels in the texture and use those directly as colliders (for a 2D game)

You can use PolygonCollider2D and then slightly edit it. Not a big deal.