https://themilkandhoneyco.com/
this company makes some nice baby sleeping bags.
The issue with making baby stuff (in the USA) are all the safety regulations involved. I doubt you will find any of the cottage gear companies (Me- LightHeart Gear included) doing this - every buckle, snap etc has to be tested for lead, and you have to have the paperwork to go with it, things like hood cords are generally a no go as they can be a strangulation hazard etc. These regulations were updated some years ago which made it even harder to do here. My business insurance won't even allow me to sew baby stuff for other companies.