Fundamentally, the faceting is caused by a limitation in resolution. Whether that be the resolution of the machine (physical size of stepper motor steps or controller) or Gcode can vary.
Carbide Create will export motion coordinates to 4 decimal places, but it does not use arc commands, which would be interpreted as mathematically perfect curves by the CNC. Instead it basically creates a bunch of tiny tiny straight line segments that approximate a circle. That is one potential source of faceting. You can try and game the system by using the Metric variant of the post processor, as the units will naturally be smaller, giving you better resolution.
The stepper motors do have a finite resolution. not much you can do about that.
The firmware of the Shapeoko also does a bit of behind the scenes magic to coordinate curved motion with the finite resolution of the stepper motors. One of its settings can be tweaked to try and maximize the fineness of curves. It is not cranked up by default, but you can try making it smaller. Enable MDI in the settings of Carbide Motion (if not already enabled), go to the MDI tab, and type in “$12=0.002” without quotes. The default value is 0.01mm which is a bit more coarse. Don’t go smaller than 0.002, or you may induce stuttering into the motion of your machine.
TLDR, you could probably do a little better than what’s shown, but there will always be a liiittle bit of faceting.