The late Derek Parfit explores numerous answers to these questions in his paper “Why Anything? Why This?”[1]. It’s hard to give a quick summary of the paper, but basically a lot of different views are considered—theism, atheism, brute fact view, etc.—and in the end Parfit seems to suggest that the existence of the universe would be somehow non-coincidental if one appeals to simplicity in ruling out or deciding between competing explanations.
I believe I can answer the question 'Why Anything'.
See my other post in thread outlining my 'Actualization Theory'. I think there's a 'ground state' of 'possible worlds' that must exist by virtue of logical necessity and some of these get 'Actualized' (become 'actual worlds') over time via the emergence of complexity (including minds and consciousness).
What I'd say is that "existence" is not binary, but rather a matter of degree, and reality is 'still under construction': the ultimate ends of the universe are the explanation as to why this universe: it's a teleological answer. The universe has to be such as allow for the existence of observers and is fine-tuned for life (because mind contributes to the ongoing 'actualization' of reality).
[1] https://www.semanticscholar.org/paper/Why-Anything-Why-This-...