A pistol shrimp won't live long unless you have a deep sand bed for it to create a burrow, and that isn't really possible in a nano tank. Also, sexy shrimp are found in nature with a host anemone, so make sure you have appropriate lighting for one.
However, all species of pistol shrimp may not need a deep sand bed, so if someone knows of one that can be kept in a nano, please correct me.