There are still plenty of Hokkaido made products available at Nijiya's SF location as of 7/23 (even after all that chaos from the ramen festival). I found out after the fact that the official dates were from 7/11 to 7/14. I confirmed with a store employee that they'll still display all products until they sell out. The display is in the back of the store between the rice and fish. Note that in the picture, the backside of the shelf contains more products in addition to a side table.
Some fun finds (some are pricey):
Potato cheese cookie ($4.99) - tastes like both potato and cheese while being sweet
Scallop butter potato chips & kelp flavored potato chips ($3.99 each)
North Farm Stock Milk Jam ($9.99) - is the pure flavor similar to dulce de leche?
Potato fries in a cup ($2.99) - not sure how they compare to Calbee's Jagabee potato fries yet (a relatively new stocked item), but they are $1 more expensive.
Corn chocolate, melon chocolate, beer jelly (only 1 left), and Hokkaido milk candies / caramels were other unique items that I saw. I verified from the ingredient list that there really were both corn and chocolate, not just chocolate bits shaped like corn kernels.
It looks like the display in the San Mateo store is bigger from Nijiya's facebook, so other stores may still have products too.