Did Ink ever go to see a scientist like Fling Dings in order to try to get a soul? Or does he not want one? The wiki said that Poppy got their soul that way or something.
Actually, I don't think he'd take one to begin with or even have one made. The first goes against his principles of nonintervention in timelines if he were to take one from someone else.
Even if he could have an artificial SOUL made just for him, having a SOUL is a liability when your enemies could rip it out of you and potentially do a lot of torment or damage to your being. While having vials and becoming a husk are huge downsides, not having that as a problem (especially with Error's strings for example), is beneficial for him. How long he will last that way with the Halving and the truce? That is something he'll have to consider in due time.
-Levi-Weaver