Specify walkable area in Unity 2D

Question

I want to limit the area where my player can walk. In this case only on red segments.

And I want to use 2D sprites as background images not 3D models. But my main player would be in 3D

Can I use NavMesh here? Or should it be done with Tilemap? Or should I place some 3D objects above it?

here is another scene that I would like to understand how to build

Answer 1

You can try adding invisible colliders attached to an empty gameobject to prevent your character from walking into certain areas.