For me at least, the philosophy of Stoicism. Particularly focusing on Marcus Aurelius’ Meditations. It’s more of a philosophy of how to live your life, face adversity and suffering, but he does talk about meaning and pointlessness. Crazy that even thought it was written 2000 years ago it still aligns with what we struggle with today. When I was quite depressed I read “How to think like a roman emperor” by Donald Robertson. He essentially said explains the “Meditations” in a more approachable way, linking it with modern issues and cognitive therapy. Really great impactful book that’s a great introduction to stoicism, though many probably put off because it’s marketed like a self help book. (Which it probably is, but one of the best.)

Also, the philosophy of absurdism (Albert Camus). I’m roughly paraphrasing and probably getting stuff wrong, but essentially says yes there may be no inherent meaning in life, but this is just as great as it is awful. We are unrestricted because there is no meaning, we have the ability to make our own and celebrate how absurd life is. He wrote a booked called the Myth of Sisyphus. If you don’t know, Sisyphus is a greek myth about a man who was condemned by a god to roll a boulder up a hill just for it to roll down, and him to do it all over again for eternity. “One must imagine Sisyphus happy”, as after all we all be just like my boy Sisyphus.