Altruism vs Egotism

Is there such a thing as pure selfishness or pure altruism? What of philosophies (such as objectivism) that promote pure self-interest? Is it possible or desirable to be selfish? Can one be purely altruistic? Is there such a thing as a purely selfless act?

Objectivism
https://www.youtube.com/watch?v=5DhWrS7WH74
https://www.youtube.com/watch?v=gd_P1n-JHWM
http://www.yaronbrookshow.com

Anthem - free download https://www.anderson5.net/cms/lib02/SC01001931/Centricity/Domain/222/Anthem%20by%20Ayn%20Rand.pdf

Enlightened Self-interest
https://www.themindfulword.org/2015/selfishly-selfless-enlightened-self-interest-myth-pure-altruism/

Is pure alturism possible?
https://opinionator.blogs.nytimes.com/2010/10/19/is-pure-altruism-possible/

If you want some heavier reading:
https://reasonpapers.com/wp-content/uploads/2018/02/rp_392_5.pdf
https://www.sciencedaily.com/releases/2016/08/160815134820.htm
http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780199583676.001.0001/acprof-9780199583676-chapter-7

The Buddhist concept of enlightenment
"Liberation means to recognise that one’s body, thoughts and feelings are in a state of constant change and hence cannot form a real ‘I’. One no longer experiences oneself as the target, which is the cause of all suffering. From this state, full enlightenment naturally follows. Here the clear light of mind radiates through every experience. The separation between the one who experiences something, the object of the experience and the experience itself has disappeared. Mind enjoys the qualities that arise in and by itself in every moment and is effortless and spontaneous in all situations."

Effective Altruism
Very Bad Wizards talk to Will MacAskill - https://verybadwizards.fireside.fm/147
- https://effectivealtruism.org.au/?gclid=CjwKCAjwo_HdBRBjEiwAiPPXpIK4KlkAxWZRd8dzzjRKpUmQ4uUbzCmDXoKY5dzIpbjtCtj1sjysyxoCTzwQAvD_BwE
- https://80000hours.org/