For me, purpose comes from my impact on other people. Is it positive? Does my existence lower the suffering of others? I don't think purpose should be comparative.

I'm not very familiar with Buddhism so I appreciate you sharing. For philosophy, I tend to look more at Stoicism. What I take away from Stoicism as it relates to purpose, is that how you live your life is more important than the things you accomplish. Living a virtuous life can be a purpose onto itself.