In short, a woodless floor go's like this.
Metal bus floor, rigid Styrofoam insulation, 14 ga galvanized sheet steel, then your finish flooring. For a finish flooring I recommend vinyl plank.
To prevent thermal transfer, all layers are glued together with a Styrofoam friendly contact cement. No mechanical fasteners.
I would not use spray foam on the floor. It would be a nightmare to get flat. Just use good rigid Styrofoam.
Hope this helps.
"Don't argue with stupid people. They will just drag you down to their level, and beat you up with experience."
Patently waiting for the apocalypses to level the playing field in this physiological game of life commonly known as Civilization