Python how to add the values in an object with the corresponding index value in a list

One way is using below

[[i,sum(x*y for x,y in zip(i[2:],[0 if v is None else v for v in is_big][2:]))] for i in prod]

Output:

[[['Pear', 'green', 2, 3, 5], 19.98],
 [['Apple', 'red', 5, 2, 10], 49.92],
 [['mango', 'yellow', 4, 6, 12], 39.940000000000005]]

You could use sorted() with a specific function score as key parameter that computes the score you need. The score you describe is the sum of a dot product with is_big, that's why converting to np.ndarray proves useful as it enables you to do dot products as easily as with a *!

import numpy as np

# avoid Nones, convert to np.ndarray to enable dot product
coeffs = np.array(is_big[2:])  

def score(input_fruit):
    input_numeric = np.array(input_fruit[2:])  # keep only numerical values
    return (input_numeric * coeffs).sum()  # dot product & sum

First, you can check that scores match your requirements:

>>> print(list(zip(fruits, map(score, fruits))))

[
    (["Pear", "green", 2, 3, 5], 19.98),
    (["Apple", "red", 5, 2, 10], 49.92),
    (["mango", "yellow", 4, 6, 12], 39.940000000000005),
]

Now sort:

# reverse=True for descending order
>>> print(sorted(fruits, key=score, reverse=True))  

[["Apple", "red", 5, 2, 10], ["mango", "yellow", 4, 6, 12], ["Pear", "green", 2, 3, 5]]

An itertools solution might be:

import itertools as it
import operator as op

is_big = [None, None, 10, 1/100, -1/100]
fruits = [["Pear", "green", 2, 3, 5], ["Apple", "red", 5, 2, 10], ["mango", "yellow", 4, 6, 12]]

fr_ranks = [sum(fr*val for fr, val in zip_one if val is not None)
            for zip_one in it.starmap(zip, zip(fruits, it.repeat(is_big)))]
# [19.98, 49.92, 39.940000000000005]

sorted_fruits, _ = zip(*sorted(zip(fruits, fr_ranks), key=op.itemgetter(1), reverse=True))
# (['Apple', 'red', 5, 2, 10], ['mango', 'yellow', 4, 6, 12], ['Pear', 'green', 2, 3, 5])

First, we align each fruit list in fruits with the value list is_big via repeating is_big and zipping it with the fruits, which will give 2-tuples of such list pairs when evaluated. Then it.starmap, with its function argument being zip, generates the desired fruit-value pairs that will reside in zip_one. A sum of products while skipping None's will give the fruit rankings.

Then we sort the fruits and this is sorting two parallel lists where the key is the corresponding element of fr_ranks. This gives a tuple but you can easily cast to list.