Since the arrays are sorted the this implies that we are interested in the max value of one of the arrays and some value form another array

e.g:

A = [5, 2, 1]

B = [31, 4, 2]

meaning we are comparing the sum [5 + 31] vs [5 + 4] vs [5 + 2] from A

AND

[31 + 2] vs [31 + 1] from B

 def findKLargestPairs(self, nums1, nums2, k):
    result = []
    
    max1 = nums1[0]
    max2 = nums2[0]
    
    max_heap = []

    for i in range(0, len(nums1)):
      heappush(max_heap, (-(max2 + nums1[i]), [max2, nums1[i]]))
    
    for i in range(1, len(nums2)): # starting from 1 we dont want repeat the value of [max1, max2]
      heappush(max_heap, (-(max1 + nums2[i]), [max1, nums2[i]]))

    for _ in range(k):
      add, array = heappop(max_heap)
      result.append(array)

    return result