The VOIDRUNNER'S CODEX is coming! Explore new worlds, fight oppressive empires, fend off fearsome aliens, and wield deadly psionics with this comprehensive boxed set expansion for 5E and A5E!
Not really either... I'm not super well versed in pf2, but It's kinda 1.5ish maybe? there are a lot of interesting things I think are probably unique to starfinder in it.
The foundation of the game is 1E although there are a number of changes, such as the way full attacks work. From what I saw of 2E they really went in a completely different direction. If you are familiar with PF1 you can pick up 98% of SF very quickly; the last 2% is a bunch of tiny changes you won't realize were in the game until you have been playing for months.