can floors be replaced on a badly rusted chevy s10 truck?
They do make patch panels for S10 floors, but you'll need someone to weld them in. If the rot is in an area that they don't make panels for, you'll have to custom fabricate your own from sheet metal. If this is for an old beater you just want to keep on the road you can always just pop rivet in sheet metal, may not be 100% waterproof though.
Or buy a junk truck with solid floors as a donor.