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