He saved the Off-color gems who would have almost certainly been killed due to Steven being on Homeworld with the hunter robots out in fuller force, presumably helped keep them alive long enough to fucking steal a spaceship out from under the noses of Homeworld's military.
Because he was off in outerspace, Steven/Stevonnie was able to go explore that jungle planet and start gaining understanding about Pink Diamond, which paid off immensely. he's also keeping the Off-colors safe(r) than they were on Homeworld.
This is a bit of a stretch, but who knows if Emerald chasing his ass all over space impacted the final battle had there not been more of Homeworld's military unloading on Obsidian during that huge ass fight.
...But seriously, guys. Are you forgetting he kept Padparadscha safe and sound this whole time???