pedrovay2003: Yup, single player, split-screen, and (I'm assuming) LAN all work without an account or the launcher running. :D
Exceed20XX: Does it change save location when you're not using service/account? Also do you know if there's any way for us to name our profiles offline? When I tested the game offline it had me as Player 1 or just a simply blank field.
I haven't found a way to customize the name, profile border, or profile banner while running the game outside of the launcher, no. Weird choices, but at least everything else works.
As far as the save data goes, it puts the save data in C:\Users\USERNAME\Documents\My Games\Rocket League\TAGame\SaveDataEpic\DBE_Production, and they're called SaveData.save, SaveData_1.save, SaveData_2.save, etc.