Interesting dimensions on a pico tank. Do a lot of reading on pico rather then nano. I personally do not like fish in pico's. The only reason I had some in mine was it was for my daughter and that is what she wanted. I would do some shrimp and softies.
With it just about 4 gals you could do biweekly 50% or more water changes with water from the main tank. Hard to put a heater, powerheads really anything in the tank