I wouldn’t eat soap simply because it’s amphiphilic, which is why, well, it makes good soap. The molecules have a hydrophilic and a lipophilic side and this will much rather soap off and severely damage the lining of your digestive route, potentially and probably also resulting in dangerous foaming.

If you take the most simple soap that’s just like potassium ions and negatively charged fatty acid residues, I’m not 100% sure but I doubt that the fatty acids want to accept a proton because they are rather stable when negatively charged, hence they won’t work well to buffer the stomach acid. And again, by the time that the fatty acid thinks about accepting a proton or not it will most likely be soaping up your cells’ membranes.