What are you talking about? Do you mean that according to the conservation of energy that nobody can explain where the energy in the universe came from? I’m going to guess maybe that’s what you’re referring to, but that not a big problem because of how gravity works. If you add up all of the total energy from objects with mass (a positive energy value) and then add up all of the warping of spacetime (a negative energy) you get exactly zero! So you don’t even need any energy to make a universe in the first place in this sense at least.
We don’t know. I think I see what you are arguing, but why can’t there be physical objects outside of our universe? Are the laws of physics metaphysical? You can make a universe if all you had were the laws of Physics in place.
But then again, what does it look like to have a metaphysical cause for anything that’s physical? Nobody has ever demonstrated what such an explanation would/could look like. No experiment has ever been performed, and the only ones that were tested failed (like the prayer experiments). The Origin of the Cosmos is only an area of our focus here because nobody knows. But everything else in the universe (besides the origin of life–the other big topic where Christian apologists mock non-Christians for not having an explanation) can be explained by natural processes. Why should this one be any different?