Here is the full list of all 37 Rebel Galaxy achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
Destroy 2,500 Fighter-Class Craft
Destroy 1,000 Capital-Class Craft
Become neutral to pirate factions
Kill 20 Pirate Lords
Break 10 blockades
Reach a Net Worth of 50 Million Credits
Find an Antimatter Speck
Purchase a Dreadnaught-class ship
Find the Face of Gozu
Find a Progenitor Shard
Complete the main campaign
Pirate a merchant
Mine 50 asteroids using a Fault Tracker
Collect 100 bounties
Break 1 blockade
Salvage 50 Containers
Complete 50 missions from the mission board
Shoot down 500 torpedoes
Gather 200 objects with a tractor beam
Reach a Net Worth of 5 Million Credits
Rescue 20 merchants
Hack 10 transponders successfully
Become friendly to the Militia
Purchase a Destroyer-class ship
Kill 1 Pirate Lord
Reach rank 5 in any Guild
Join the Mercenaries' Guild
Jump out of the first solar system
Destroy 100 Capital-Class Craft
Trade with a Merchant while in flight
Hire a mercenary
Collect 10 bounties
Destroy 250 Fighter-Class Craft
Join the Merchant's Guild
Successfully bribe a Militia official
Woke Trell
Purchase a new ship