What exactly are you looking for when you say shockwave? As far as we understand it, the big bang didn't explode into something, so there isn't an outer medium

What exactly are you looking for when you say shockwave? As far as we understand it, the big bang didn't explode into something, so there isn't an outer medium to "hold" a shockwave in the obvious sense of a radially expanding region of turbulence. Also the frequently depicted diagram of expanding from a point doesn't really intend to depict the shape of it. The universe might still be infinitely large and the big bang occurred "everywhere" within it. Where is the shockwave in something that has no edge?