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