The camera phone module has sailed for the camera makers except eg Sony (who is producing such units), the level of technology and miniaturisation inside those little cameras is truly astounding. It is rumoured that at least a thousand engineers are working on the cameras inside the iPhone, how many engineers are working now on the X-T3??
As long as those cameras are kept so small, they will remain severely photon starved in comparison to any ILC we know today.
But the smartphone camera is not about state of the art picture quality, it is about the "always with me and connected" convenience. The camera makers have extreme difficulty with that.