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