Sammy knows Undertale is, so he decided to do the same thing they do with the souls, but tweak some stuff. Its not really the embodiment of your being rather a way to make you pass out, but its not the same case for Sammy if HIS soul gets destroyed he will sort of die but it will repair itself and he gets turned into a monster, now if that soul gets destroyed he turns into an entities which basically means you aren't normal at all. only he has it and it doesn't really work like undertales or deltarune souls bc he can pull anyone's "soul" out of them and destroy them, it doesn't kill them it just makes them go away for about a week.