We used this baby carrier cover. It has elastic all around the edge, so I would layer up baby a bit and put him in and then put this one around the carrier. It covered up his feet well. If it wasn't too cold I did this with my jacket just opened and him on front. When it got colder though I zipped up my jacket around me and then put the carrier on top. This has pockets in the front which is nice to keep my hands on him and also warm.
Soft booties that have a velcro strap at the ankle, like others have mentioned, are great.
I wore babycarrier blankets/jackets from Uniqlo and Amazon Japan. I just searched Amazon US and found this similar type of carrier blanket: Jolly Jumper Snuggle Cover for Soft Baby Carriers, Black https://www.amazon.com/dp/B001P1VBH4/ . Good luck!
oh yea, they are universal. it just hands around your neck to cover the baby. it doesnt connect to the carrier in any way. Heres an example.
For baby wearing, I used the Jolly Jumper cover. I made due with my regular coat and this and trying to kind of keep things wrapped up but I probably should have sprung for some sort of baby wearing jacket or extension for my coat. I dressed kiddo in layers and zutano fleece booties. Look for fleece-lined knit caps, there are tons of options out there. They will say like 0-6 months usually.
If you do something over the car seat, make sure it's a "shower cap" style. Meaning it has elastic to go around the car seat and doesn't have the harness thread through holes in the cover. Something like this JJ Cole cover.
My first babe was born in November and we live in the upper midwest. We did lots of baby-wearing because our town is terrible about clearing sidewalks and they were impassable in a stroller.
I use this thing over a baby carrier with my baby: https://www.amazon.com/gp/product/B001P1VBH4, you can also put it over a car seat or stroller.
I’ve heard several people say that the jolly jumper carrier cover works well. jolly jumper amazon