public function vendors(): Collection
{
    return $this->belongsToMany(Vendor::class);
}

public function index(): Response
{
    $products = Product::with('vendors')->get();

    if (!$products) {
        $productsNotFoundMessage = 'Nie znaleziono produktów';

        return view('products.index', compact('productsNotFoundMessage'));
    }

    return view('products.index', compact('products', 'productWithoutSuppliers'));
}


view:

{{ productstNotFoundMessage }} // Not sure if it will interpolate it as ''

@foreach($product->vendors as $vendor)
    {{ $vendor->name ?: 'Nie znaleziono dostawców dla tego produktu' }}
@endforeach