Here is the full list of all 50 Starfield achievements. It takes around 100-120 hours to unlock all of the achievements on Windows.
Modify a Ship
Reach Level 10
Reach Level 5
Join Constellation
Enter Space for the First Time
Complete "Into the Unknown"
Complete "All That Money Can Buy"
Complete "Further Into the Unknown"
Complete "High Price to Pay"
Complete "In Their Footsteps"
Complete "Entangled"
Complete "Unearthed"
Complete "One Giant Leap"
Join the UC Vanguard
Complete "The Devils You Know"
Complete "A Legacy Forged"
Join the Freestar Rangers
Complete "Surgical Strike"
Complete "The Hammer Falls"
Join Ryujin Industries
Complete "Guilty Parties"
Complete "Executive Level"
Join the Crimson Fleet
Complete "The Best There Is"
Complete "Legacy's End"
Build an Outpost
Connect 5 Outposts with Cargo Links
Produce 500 Total Resources from Outposts
Visit 20 Star Systems
Visit all Star Systems
Land on 100 Planets
Complete 30 Activities
Complete 30 Terminal or Misc. Missions
Gather 500 Organic Resources
Gather 500 Inorganic Resources
Bypass 50 Digital Locks
Access 50 Computers
Mod 50 Weapons
Craft 100 Items
Recruit 10 Separate Companions
Reach Maximum Relationship Level with a Companion
Collect 20 Quantum Essence
Collect 10 Ships
Read 20 Skill Magazines
Eliminate 300 Human Enemies
Eliminate 300 Creatures
Successfully Smuggle Contraband
Reach Level 25
Reach Level 50
Reach Level 100