the save data is actually in the windows registry at Computer\HKEY_CURRENT_USER\Software\RegulusNSFW\StarbreedDemo
the relevant hexadecimal values (base 10 in parentheses) for unlocking all v0.9/v0.9.x content should be these (i clipped off the "_###" stuff):
assertion = 64 (100) [aether's assertion]
resolve = 64 (100) [aether's resolve]
charAff0 = C8 (200) [aether's affinity]
charAff1 = 31 (49) [lana's affinity, remaining scenes not yet in game]
charAff2 = 64 (100) [pix's affinity]
charAff3 = 64 (100) [siren's affinity]
charAff4 = 31 (49) [tanya's affinity, remaining scenes not yet in game]
charAff5 = 31 (49) [nika's affinity, remaining scenes not yet in game]
charAff6 = 31 (49) [rooster's affinity, remaining scenes not yet in game]
credits = 2710 (10000) [shop credits, if that's not enough to buy everything just increase the hexadecimal value]
(the names and their corresponding levels below are most likely subject to change as levels get added)
levelScore0 = 6E (110) [catiya1 high score]
levelScore1 = AA (170) [pix1 high score]
levelScore2 = 96 (150) [pix2 high score]
levelScore3 = 96 (150) [siren1 high score]
levelScore4 = F0 (240) [siren2 high score]
levelScore5 = AA (170) [rooster1 high score]
levelScore6 = C8 (200) [lana1 high score]
levelScore7 = 96 (150) [tanya1 high score]
levelScore8 = A0 (160) [nika1 high score]
make sure you edit these values when the game is closed!
i think you'll have to beat each character's first level once to unlock them on the main menu/the hscene gallery and have the edited high scores and level trophies register, i didn't want to the unlock flags for these down because i'm sure it has to do with all the flag or level values and fucking around with those ones specifically might break the game
i'm sure that once the game is released on steam and wherever else that the save will be in an actual file and not the registry, because that's the case for the dev's previous game spunkstock (the save data is in the registry *and* in an actual .dat file), but this is just how it is for now