Here is the full list of all 11 Hacknet achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Complete Bit's final request
Run ThemeSwitcher
Run Clock.exe
Be granted an account within CSEC
Master of /el's friendly community
Disconnect from a traced system with less than half a second to spare
Have a truly absurd number of pointclicker points
Purchase the final PointClicker upgrade
That's just impolite
Complete the tutorial earlier than normal
Be granted an account within Entropy