So, tracking the announcements so far:
3/29/2021, 4 million
4/04/2021, 5 million
4/27/2021, 6 million
5/27/2021, 7 million
They are selling about 1 million a month at this point, but obviously the rate is slowing. I'm thinking they will hit 8 million sometime in July. This game definitely has legs.