Week 1:
NA ~1.1M
Week 3:
UK -250k
Europe rest ~420k
Rest of world ~130k
Total from launches ~1.9M
Total after second launch =2.1M (due to ~200k extra sales in NA)
PS5 is basically launching in the same countries as PS4 plus a few Asian countries. Auz and NZ move to week 1 instead of being the second launch and Japan, SK and Singapore are also week 1. So here's my estimate for PS5:
Week 1:
NA ~1.25M
Rest ~225k
Week 2:
UK ~275k
Europe rest ~475k
Rest of world ~125k
Total launches ~2.35M
Total after 2 weeks ~2.5M
Could be way off with some of those but hey ho, this was just for fun. I think I'll be close overall. Its total after 3 weeks will be >3M, well ahead of PS4's 2.1M.