Maybe a coule small fish but your stocking options are very limited. Shrimp make a good small tank addition. THe snails will be ok as long as they don't get too big and you don't overfeed.
As for specific fish, maybe a couple guppies, a sword, a beta, or a platty. If you get guppies get the same sex so they don't reproduce by the hundreds.
If you don't cycle the tank, it will slowly kill most fish you put in there and could kill the snails. The side effects are replacing fish a lot because they won't live very long. Eventually it will cycle on it's own but the fish will suffer. Lots of water changes will also be needed to keep the water clean enough to protect the fish.
Most poeple buy small tanks to start because they think they are easier than bigger tanks, but in actual fact, a bigger tank is easier to maintain, as nitrite and ammonia is diluted in a larger amount of water.
As people have said, you could put a betta or a couple of guppies in the tank, but apart from that, the stocking choices are VERY limited.
Even a 10 or 15 Gallon tank would open up many more options for you and your tank.
Whatever you decide to do, good luck.
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