Nut Butter Packets:
These almond butter packets from Justin's are the most convenient keto snacks ever! Great macros, tiny little packets that fit in backpacks and purses, and super yummy! I always have one of these in my purse for a quick bite. I got a great deal on them from Costco so check your local Costco to see if they carry them.
There are also peanut butter packets that I like a lot. I just try to make sure there's no added sugar and not too much salt. I opt for raw everything as often as possible.
I buy HUGE jars of olives and snack on them throughout my day. They're fantastic fat and satisfy my salty/sour cravings nicely. I'm a particular fan of green olives but any will work, especially if you get the kind that come in olive oil!
Pickles aren't fatty but they are super low carb and usually have no or extremely low calories so they're perfect for snacks. I know not everyone likes pickles so this may not be for you. I personally can't ever eat enough pickles so these are a snack I always have on hand that won't break my keto macros.
There are a few nuts and seeds that I rely on heavily in keto: almonds, walnuts, hemp hearts, chia seeds, flax seeds, and pumpkin seeds. I usually make a mix bag of almonds, walnuts, and pumpkin seeds to take with me for a snack. I sprinkle hemp hearts on almost all my savory meals. Then, I cook with chia and flax to thicken my baked goods and smoothies.
Give those a try and let me know what else you snack on in vegan keto!