The correct part is SST25VF020B-80-4I-SAE
Now, the 020 portion there denotes the number of bits of storage. So you can use any capacity of flash in this class to store more user data. And yes, it would only be for storage, not for user code.
Just be careful to get the 80MHz version. There is a very similar part that runs at 20MHz that wouldn’t be compatible. The -80- near the end denotes the 80MHz version