The original announcement about the return of Spelljammer was originally thought to be an April Fool's joke. But it was real. So, one might think that the announcement for Spelljammer minis is also a joke. But, I'm going to bet it's not. Also, there's no May Fool's.
From the announcement:
You don’t even need a spyglass to see the cosmic treasures that abound in the upcoming D&D Spelljammer miniatures collection. The new trailer was featured at D&D Direct – Watch Now!