No
No, you cannot. Big costs, small blankets, etc can be brought in but you need to be able to open them all the way up. Dress in layers.
I cannot speak for official venue rules specific about sleeping bags. But many folks inside brought blankets and thermal wraps. Same type protection. Also many sleep bags unzip and are actually when unzipped merely blankets with irritating edges.
No, maybe a blanket
Blankets are allowed. Expect to shake them out at security. Sleeping bags? I'm not sure.
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