I like Sarah Bakewell even though I have never met her. She is a librarian or was at one time and lived in London. She is the author of How to Live, At the Existential Cafe and other books. How to Live is about Michel de Montaigne (1553-1592), often labeled as the inventor of the essay, short writings on a subject. I was reading At the Existential Cafe, an examination of the philosophy that grew from Kierkegaard and Husserl to post-war France. From what I know of Buddhist and Hindu philosophy, brain science and life practice advice, the existentialists may have missed their mark.
There was writing, speech and discussion about the Ding an sich, German for "the thing in itself", or unadorned direct consideration of the world. But today, perception scientists recognize that in some ways, humans cannot perceive anything directly, There is so much going on between the eye, the optic nerves, the recognizing brain and the classifying, perceptive brain, and there is so much going on in an object with its atoms and molecules and the lighting involved and the timing, and my history of perceiving such objects along with my learned understanding of the sinfulness or glory of such objects that "the thing in itself" is a myth and a concept and a memory.
That doesn't mean that when I stub my toe, that I didn't hit something. It does mean that parts of me know about the stone that stubbed me before other parts. It doesn't mean that my perception equipment and habits are worthless. It does mean that there are more layers between me and the world than are easily known.
I suggest that existentialists focus on appreciating the miracle of being alive and sentient, of having the perceptive abilities they have, and enjoying what they can do and have done in life. A useful approach is temporary cessation of thinking, of theorizing, of "doing philosophy", and simply being a human in myself for a few minutes.