Your real Fortnite play unlocks skate. — gear, parks, the whole map.
Locker Drop reads how many real Fortnite matches you've actually played (counted from your own Fortnite install's local replay files — nothing is guessed or copied) and uses that to unlock skate. for you, every time you launch:
It runs on top of ReSkate, the open-source offline/mod runtime for skate. (bundled here, unmodified, under its GPLv3 license — full credit to the ReSkate team). Locker Drop adds one small step before ReSkate starts: it checks your real Fortnite play history and writes the matching unlocks into ReSkate's own save data.
Nothing from Fortnite's game files is read or copied — Fortnite's actual assets are encrypted and off-limits. Only the fact that you've played, and how much, comes along for the ride.
Solo play. Needs Fortnite and skate. both installed.