Build a world map with showing player's progress

I am building a World Map as a separate scene for my mobile game. This scene shows World Map with Key Points which Player should pass to make a progress. Points are shown in black/white by default and change to colored image when passed. The total number of Key Points are about 400.

I attached a screenshot with a piece of map. In the bottom right corner are 3 passed points (colored) other are black/white.

My question is: what is the recommended approach to check for Point's status and change its image to colored considering that this is a game for mobile and we have about 400 game objects?
Note: we only have to do this once on scene load.

The first idea was to have each point as a separate UI Game Object with an Image component attached and a MonoBehaviour script. The script would hold references to both sprites (black/white and colored), check the status of the Point in Start() and choose the correct sprite for the Point.

I am not sure if this is a good idea to have 400 MonoBehaviours in one scene, even though they will not do any Update(), only quick check in Start(). I would be more confident, but I don't know how to profile this approach and will appreciate any advice here as well.

 

Well, what I ended up doing for a client game was just setting each one as a level, and making it so they couldn't go further than the level they completed. Each box/visual tile on the pathway had a little trigger box collider that the player tapped, and it had a little script with parameters for the level number, name, scene name to load, etc. I just used two different sprites, one for completed, one for incomplete. Worked fine. Just changed the sprite when I needed to and saved it.

 

How many visual tiles did you have on your pathway?