Infant sit-me-up

AB

So my son is 12 weeks old and a temporary Pedetrician that we took him to told us to get him a sit-me-up sort of seats for him so he can sit up on his own. I didn’t know they make those for infants this young? Does anyone know what she is talking about or should I not listen to her? I just feel like 12 weeks is too young to be sitting in one of those without my support...what do you think?