Would a tunic style do?
Are we talking just one blanket?
Do you want sleeves? If so, fitted or wide open? How long?
buttons/zip/ laced?
belt or tailored waist?
Is the blanket long enough that folded in two it would cover your bum?
I’ve made a sort of basic robe out of boiled wool which is very like blanket, no buttons or zip and cinched into what I call my waist with a belt. For the sleeves, think sort of wizard .
That was very easy to do in 3.5M of 1.4M material for a floor length shirt.