My Cory eggs are always eaten by the tank mates.
Maybe you can get an order in for a few foods and eventually they will come, and so you will have more options. I have seen some individuals use some normal fish food with additional found/gathered foods and blended together with a prepared gelatin, like you get with a Rapashy food.
You tube shows lots of ways to make foods yourself, and you could adapt it to your own ingredients. Maybe good ideas using the tools and cooking equipment you have on hand as well.
One thing I do make is ice cubes of greens for the fish and snails. Just fill up the ice cube spaces with garden greens, bits of blanched vegetables they might eat and add filtered water. Freeze remove cubes and put in a container in the freezer. Drop one in periodically. I should do this myself soon! I don't have any more in the freezer!