AssetDatabase.GetMainAssetTypeAtPath

Получает тип основного объекта ассета.

Все пути относятся к папке Project, например: "Assets/MyTextures/hello.png".

using System.Collections.Generic;
using UnityEngine;
using UnityEditor;

public class AssetDatabaseExamples : MonoBehaviour
{
    [MenuItem("AssetDatabase/Print Type Count")]
    static void GetAllAssetTypeCount()
    {
        var typeCount = new Dictionary<string, uint>();
        //Put all the types that were found in the typeCount dictionary and increment their count
        foreach (var guid in AssetDatabase.FindAssets("", new []{"Assets"}))
        {
            var path = AssetDatabase.GUIDToAssetPath(guid);
            var typeString = AssetDatabase.GetMainAssetTypeAtPath(path).ToString();
            if (typeCount.ContainsKey(typeString))
                typeCount[typeString]++;
            else
                typeCount.Add(typeString, 1);
        }
        //Print types and their count into the Unity Console
        foreach (var element in typeCount)
        {
            Debug.Log(element);
        }
    }
}