List inside of List: Multi-Level Data

php artisan make:model Product -mf

public function up(): void
{
    Schema::create('products', function (Blueprint $table) {
        $table->id();
        $table->foreignId('category_id')->constrained();
        $table->string('name');
        $table->text('description');
        $table->integer('price');
        $table->timestamps();
    });
}

use Illuminate\Database\Eloquent\Relations\BelongsTo;
 
class Product extends Model
{
    use HasFactory;
 
    protected $fillable = [
        'name',
        'description',
        'price',
    ];
 
    public function category(): BelongsTo
    {
        return $this->belongsTo(Category::class);
    }
}

use App\Models\Category;
 
class ProductFactory extends Factory
{
    public function definition(): array
    {
        return [
            'name'        => fake()->word(),
            'category_id' => Category::inRandomOrder()->first()->id,
            'description' => fake()->paragraph(),
            'price'       => rand(1000, 99999),
        ];
    }
}

 
use App\Models\Product;
 
class DatabaseSeeder extends Seeder
{
    public function run(): void
    {
        Category::factory(10)->create();
        Product::factory(20)->create(); 
    }
}

php artisan migrate:fresh --seed

php artisan make:controller Api/ProductController
php artisan make:resource ProductResource

Route::get('/user', function (Request $request) {
    return $request->user();
})->middleware(Authenticate::using('sanctum'));
 
Route::get('categories', [\App\Http\Controllers\Api\CategoryController::class, 'index']);
Route::get('categories/{category}', [\App\Http\Controllers\Api\CategoryController::class, 'show']);
 
Route::get('products', [\App\Http\Controllers\Api\ProductController::class, 'index']);