Most animations are on being beaten by enemies, but as far as defeat goes it's really generous. Most of the time you get taken off to a side room somewhere for the scene, in some places it even progresses you into the area, then you get up usually with enough time to get a free shot in the back of whatever enemy beat you. The few game overs (Ones I remember is getting shot by Spec Ops in most area, Losing to the Alpha 3 times or during their boss fight and getting beaten in some sections (Escorting Miho at the end of Botanical)) just boot you back to the start of the area or checkpoint. Biggest exception I would say is the Hub Defence, Supply Run and soon the Sabotage side missions, as they have (or will have in Sabos case) an escape mission tied to if you lose, which mostly gives you some scenes (in Supply Runs defeat scenario you can skip the whole level by finding a switch in the first area but it's honestly not that hard once you figure out where to go, and afaik it has 1 scene unless I'm dumb(very likely))
As far as "Sandbox" goes, once you unlock them you can replay any level from the hub except the Pre-Hub zones but no, it's not an open game and is fairly linear in terms of progression. No Gallery either, but with the ability to replay levels you can access pretty much every scene bar 1 (Getting held up by a Spec Ops guy in the Pre-Hub section) as most are just tied to getting beaten up by Spec Ops (in melee) or Werewolves. There are multiple scenes in the Hub but sadly it includes a few non-repeatable ones (iirc the Doctors scenes can't be replayed and take a while with how much dialogue he has).
Biggest thing I wish this game had was saves so you *could* go back to parts of the Pre-Hub area, there's missable outfits there if you don't grab them but losing all your progress to get them is a bitter pill.
