aPixie Snuggle nests got discontinued, something to do with the foam not being safe/fumes I think.
OP I'm not convinced my 5 months old couldn't inchworm out of that, and he would try as he likes to snuggle in close to me (he chases me across the bed at night until his dad falls out and he is in the middle in a star shape).
Bed rails would be my recommendation. I got some foam ones (brand is bed bugs) that are like bumpers that go under the sheet, on ebay for about a fiver each. They are really good for going away too.