This is a problem related to a typical e-commerce requirement.
I am using ElasticSearch for all the below use cases.
I am confused about whether or not to use MongoDB for the sorting part.
I have the data in the following format:

Product JSON:

{
  "name": "String",
  "description": "String",
  "characteristics": [
    {
      "name": "Brand",
      "value": "Apple"
    },
    {
      "name": "Color",
      "value": "Red"
    },
    {
      "name": "Storage",
      "value": "64GB"
    },
    {
      "name": "stockStatus",
      "value": "IN_STOCK"
    }
  ],
  "prices": [
    {
      "priceAmount": 100000,
      "discounts": [
        {
          "discountAmount": 300,
          "conditions": [
            {
              "name": "primeCustomer",
              "value": "true"
            },
            {
              "name": "oldCustomer",
              "value": "true"
            }
          ]
        },
        {
          "discountAmount": 500,
          "conditions": [
            {
              "name": "deviceType",
              "value": "premium"
            }
          ]
        }
      ]
    }
  ]
}

I want to

1. Search based on name or description.
2. Filter based on characteristic name and value.
3. Sort based on the discounted price.
4. Pagination
5. Filter products lying at a particular price(discounted) range.

Multiple discounts can be applicable at the same time – like in the above example, the customer is prime+old as well the device is premium. I want to evaluate the conditions on runtime based on the input parameters and then sort the results based on the final discounted price.

I will definitely run benchmarks for both ES and MongoDB but before that, I would like to know are there any recommendations for this type of scenario?

I have to operate on millions of product documents.

Right now, I precompute all the possible combinations of the conditions and then create a single price document for each combination to avoid any calculations on the runtime. But the combinations are too much given the conditions are increasing every day with new business requirements.