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