I was wondering, can't immediately find an answer to this but, in endgame collapse, if the killer closes the hatch and you have a key with you, is it possible to re-open it?
I think so, they closed the hatch, not broke it
Yes.. you can open it back up and escape.
Also he can close it again after you open it. So if you open right in front of him and try to jump he can interrupt your escape animation by closing the hatch again.
"Jokes on you! My key is reusable!"