Just a little work and it could be.
I looked hard at adapting it - the frame rails are about the same width, but the pickup bumpers are designed to sit outside the frame rails. There's a body mount in the way on the 4Runner, so you'd need to move the brackets in a smidge to fit inside the frame rail, or cut/modify the body mount. In the end I decided it's not exactly the bumper I want and not to put in the effort, but it's doable.