Just looking a few examples for you:
FAS8200/ A300/A700 running ONTAP 9.5 Maximum number of open files is 1,500,000.
FAS2650/2750/A200/A220 - Maximum number of open files is 600,000
(all values per HA pair)
Keep in mind there is a lot more to sizing and configuing a system then just the open file metric. I do a lot of these for customers, let me know if you have any questions.
All this can be found on the HW - https://hwu.netapp.com