Here is the full list of all 8 Pivvot achievements.
You are a masochist!
Survive for 100 seconds in Random Expert Endless
Complete the Expert Voyage mode without a single death
Survive for 100 seconds in Random Endless
Get to Wave 5 in Looper mode while only turning in a single direction
Complete the Voyage mode without a single death
In Looper mode, complete five loops in a row without stopping
Survive for 100 seconds in Berserk