In the US, "they" is a pretty common singular, non-gendered pronoun. I could see either "they" or "it" being used, depending on sentence structure, but not necessarily due to plurality or countability.
Notice “skate” versus “skates” in these cases:
- Alice skates; Alice is a skater.
- Alice and Bob skate; Alice and Bob are skaters.
- She skates; she is a skater.
- You skate; you are a skater.
- You skate; you are skaters.
- They skate; they are a skater.
- They skate; they are skaters.