Also I would have added an extra button at the top as it is a bit too low cut although it can be easily corrected by sewing a snap fastener. Pockets are unneeded from my point of view. I usually prefer unpocketed onesies since they add an unnecessary bulk on the sides and are not really needed but since lightweight Calida jersey cotton is not heavy they are not uncomfortable.
Please note it fits VERY loose so I suggest going down a size than your usual size.
All in all, quite nice to be Calida’s first all in one effort although needs some improvement. Wish they come in a wider range in the future without belt and pockets.