I have had some weird ones with muzzleloaders, but not so much with cartridge guns. What’s really interesting is to think about such a slow hang fire in another gun...
revolver... jams against the frame and either spits lead like crazy or if it goes at the 6oclock it hits frame, blows the cylinder walls out and you hope to have fingers left.
pump gun... shell pops when it hits the ground. Schrapnel isn’t super dangerous but you would expect to catch some, and expect to have it removed at the clinic.
semiauto... if you can’t restring your to a tap/rack situation. Assuming it shoots as you reach for the slide or the bolt handle it can bite hard and fast. AND your probably looking down into the chamber as it comes out, so hopefully you have your eye protection on.
lever... if it goes while your opening the gun it could break a hand pretty easily. It would probably wreck the gun too as the bolt slammed to the rear and may keep traveling back at you. Slamming open from a round detonating would do damage.
I have heard claims of slow hangfires, and I have had some really weird ones with shotgun shells that got wet. It is, in my opinion, one of the most dangerous situations a shooter will encounter, as things may go bad at the exact time you give up on it and go to remove the round or investigate. Scary stuff for sure.