I had an idea that a place to buy things with your hard earned coin would make sense. Well, some sense. You are playing as a dog after all and having money doesn't really work. BUT I DIGRESS. The point being, it's nice to have an aspirational long term goal as well. You reach the store, you see an item that you just got to have and now you've set your own goal. No need for a quest structure because the player has set a goal for themselves.
Building a store is tough though. Originally my idea for the game didn't really have items. So having things that make sense for a dog to collect and use is hard to come up with. In addition just coding it has taken me a while. I realized I made my inventory system not very generic, so I couldn't really reuse parts of it. So I have to refactor some things so I don't end up with duplicate code for essentially the same thing.
I don't know that many people are reading this yet, but if you see it, let me know your ideas for items a dog might use!