Unity 2D - Use Digital Painting as Terrain

Hello People,

I was wondering if anyone has tried to use a digital painting, created by an artist as the terrain/Environment for the game. I know if I had every Walkable/Intractable part of the drawing as a separate sprite, then I would be able to use them as an individual object and add colliders, effectors, etc. But the digital painting is one file so chopping it up manually is not my first option.
I was thinking of including empty objects and just adding line colliders to them and put them in proper places so it would work as if the character is walking on the walkable parts of the terrain or interacting with interactable parts. Are there any better approaches to this problem?
Thanks in advance.

I made once a Prototype with 2D Maps. I painted it in Photoshop in diverent Layers. One for the Ground. One for Walls. And one for things above the Player. Unity can Read PS files. The Layers will be seperated Sprites. I also made a PS Layer with orange lines for some level Borders. Just add a Polygon Collider and put the Sprite Layer to 0