Just out of curiosity what do you guys think? The buckle strap is the only car seat part that goes through the sleep sac. It's fleece so not it's not bulky. This is basicaly the original sleep sac with a whole for the buckle strap so you don't have to squish all the excess fabric between baby and buckle. But does it technically "interferes with the harness"?
https://www.halosleep.com/products/detail/?product_id=252
https://www.halosleep.com/products/detail/?product_id=252