I am arriving into Changi at 12:20 am on JAL (T1) and departing on Scoot (T2) at 9:00 am . I believe that I will need to go through immigration and collect bags, correct?

I have priority pass, and I’m hoping to be able to recheck and get airside to get a few hours sleep in a lounge. Looks like check-in counters for scoot close at 1:30 am. Any suggestions on the best lounge to head to if I can get airside again? Worst case, I think there is a landside lounge in T3? Thanks so much!