How to check if any/multiple 2D sprites neighbour/collide with eachother
Hello. I am making a strategy game with a map. On this map, there are multiple territories in the form of sprites with a 2D Polygon Collider attached to each one of them. I've mostly figured out things regarding the map itself, but what I urgently need is a way to check if two sprites neighbour eachother, and then print that data. For example, on sprite click it would say "Territory1 neighbours Territory2 & Territory3 &...".
I have tried two methods for this approach. The first method was to manually store data for each sprite, which proved to be quite tedious since I have a large number of sprites. The second method was to check for the distance between sprites or to check for collision between the 2D Polygon Colliders, but I've only come across tutorials/solutions that apply to only two sprites (& two colliders).
So then, I've been thinking to implement a variable which I could input into each sprite. This variable would tell the game how many neighbours each sprite has, and then the game would check for collisions/distance (hope this isn't too complicated to understand?) & print the needed data.
I know my problem is really specific and I'm at least hoping there's someone who could help me solve this. By all means, suggest any other implementation you would see fit. Cheers :)