Supremacy was a September release in 2019, but only Footy Stars (March) and Dominance (June) releases in that year.
Supremacy was November in 2021, after Footy Stars (March), Prestige (May) and Optimum (September).
I think a Series 2 in September and Supremacy in November seems likely. I don't think they'd be having players sign cards over a year out from release. Though they could be thinking Supremacy in the middle of 2025.
In Series 2 I would LOVE a parallel set done like the Select 1994 cards, classic design and would look sick.