Yes they can have one at 1 but it's parents decision x
I have a duvet and a pillow for my little one and he’s just turned one, he hated sleep sacks etc and the duvet has made a difference I made sure to get a thin cot bed duvet for him and a really thin pillow so it’s breathable
I use a 100% wool knitted blanket, it’s good for a range of temperatures, has a nice “heavy” feel while being very breatheable
I recently got my 13 month old a duvet and pillow and he has slept so much better since having it x
What about a footless sleep sack? Would that be better? Or a cellular blanket x