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