Do you have a fluorescent bulb? If so, then there’s no reason that you shouldn’t try your hand with a few plants. Most plants will quickly overgrow such a small tank, so try plants like banana plants, moss balls, or anubias.
Your fishes’ waste should produce adequate fertilizer, but you can also pick up some trace elements (phosphorous etc) for plants (macros and micros), but only use a teensy bit.