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