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