Open the MRG in HxD and see if there's anything that says 'bres" in there. If so, try opening it with Brawlbox. I doubt it uses MDL0s, but it's worth a shot.
Nothing in there that matches "bres" and tried to open the .MRG in Brawlbox anyways, and the program stops working.
I think that the games use .obj format for models, I opened the .bin file for Kratos in HxD and I could see some offsets for bones and some strings that I think had .obj in them.
I have no idea how to extract it, though.