How to add many objects to database in Django TabularInLine?

Question

Django

I currently need to add many objects to a pass-through table using python manage.py shell.
I will describe the models here in a nutshell, I will not litter with extra fields.
So I have a Product model:

class Product(models.Model):
    name = models.CharField(max_length=200, db_index=True, unique=True)
    slug = models.SlugField(max_length=200, db_index=True, unique=True)

Next, I implemented the Shop model:

class Shop(models.Model):
    name = models.CharField(max_length=200, db_index=True)
    slug = models.SlugField(max_length=200, db_index=True)

I need to have a through table where I would regulate, for example, prices inside the store and balances inside the store, so I implemented the ShopQuantity model:

class ShopQuantity(models.Model):
    shop = models.ForeignKey(Shop, blank=True, on_delete=models.CASCADE, null=True, related_name='product_list')
    product = models.ForeignKey(Product, blank=True, on_delete=models.CASCADE, null=True, related_name='shop_list')
    price = models.DecimalField(max_digits=10, decimal_places=2, default='0')
    quantity = models.IntegerField(blank=True, null=True, default='0')

For clarity, I will present here what the admin panel looks like for this structure:

class ShopQuantityInline(admin.TabularInline):
    model = ShopQuantity
    extra = 0

@admin.register(Shop)
class ShopAdmin(admin.ModelAdmin):
    fields = ['name', 'slug']
    list_display = ['name']
    inlines = [ShopQuantityInline]

@admin.register(Product)
class ProductAdmin(admin.ModelAdmin):
    fields = ['name', 'slug']
    list_display = ['name']
    inlines = [ShopQuantityInline]

Let's say I already have 1000 items in the database. Can you please tell me how can I put these 1000 products in the Shop table. I know it's possible to use manage.py shell, but I don't understand how.
I can create 1000 objects for the store using a regular loop, but I get just empty entries (in this example, I just create 5 entries):

for i in range(5):
    p = ShopQuantity.objects.create()
    p.save()

The image shows the usual ShopQuantity pass -through table for the Shop table . Exactly what I would like:

and so on up to the number of products available in the database (if there are 1000, then 1000)
If anyone has encountered this and solved this problem, please help.