If you are using build123d, probably the easiest way is to sketch an ellipse and revolve it.
The definition of an ellipsoid is that it can have three independent radii. A revolved ellipse only has two independent radii. If only two independent radii are needed then yes I agree with you, but I wanted to provide a fully qualified answer.
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The definition of an ellipsoid is that it can have three independent radii. A revolved ellipse only has two independent radii. If only two independent radii are needed then yes I agree with you, but I wanted to provide a fully qualified answer.