You could possibly have two or three red cherry shrimp (Neocaridina heteropoda) in a tank that small, or some tiny snails. That's about it. They're pretty hard to kill, honestly - they eat the biofilm found in cycled aquariums and would benefit from an occasional blanched veggie or two. I see sand as being better as it'd probably let them scuttle around more comfortably, but gravel would work too.
Live plants would definitely be a plus, as shrimp love them. You could get some java moss (one of the hardiest plants out there) and a small rock or two, and maybe something taller like hornwort or a crypt-type plant. It'd allow for better oxygenation of the water (plants absorb carbon to produce oxygen) and keep the water clear.
As for cycling, I'd get a small hang-on-back filter like the ones from Red Sea or TOM (undergravel filters aren't really used anymore), some sponge media, and some media that has beneficial bacteria on it, such as a sponge from someone else's established tank. The pet store might lend you some. It'll take a few weeks, but it would be worth it.
