So I'm at home and unable to go out to the store to buy Chunky Peanut Butter for a almost instant no-bake cookies. Does anyone know if there is a possible substitute to use?
One solution is to make your own peanut butter.
If you have peanuts (preferably roasted; if you have raw peanuts, toss them in the oven on a baking sheet in a single layer at around 350 F for about 10 minutes, maybe with a tbsp of peanut/vegetable/canola oil), throw them in a food processor or blender and let it rip. Scrape the sides of the bowl periodically. You'll (eventually) end up with peanut butter.
If you want chunky, run the food processor until the peanuts are chopped, reserve a portion of them and then run the food processor until the rest is smooth. then, put the chopped peanuts in and pulse to combine (or just stir them in).
Season with salt and sweetener (e.g. honey) to taste.
Note that this is going to be relatively expensive versus just buying a jar of peanut butter.
The usual substitutes for peanut butter are other nut butters like almond butter. See this question for some common substitutions. Or, make a different type of cookie.
Probably the only direct substitute would be another similar nut butter: smooth peanut butter (with chopped nuts added if you want the chunky texture), or maybe almond butter or some such.
It's possible that if the recipe expects extremely finely-ground peanut butter (think Skippy or Jif), then less smooth "natural" butter might not yield the same texture, though. This is especially a concern with no-bake cookies, where you likely don't have as much structure from flour and such, so messing up the texture might mean they just don't set right.
There are also plenty of other no-bake cookie recipes out there, so looking for a different recipe might be a good call if you don't have what you need and you really want them to come out right!