My understanding is that "Ownership in Rust is entirely a type system fiction." is a fancy way of saying that, if you look at the generated machine code, you can't "point at the ownership".
It's purely a constraint on which programs will be allowed to compile, similar to how machine code has no concept of variable types. They're just constraints in the compiler so you can't accidentally call the floating point addition opcode on bit patterns representing integers without first specifying how to reconcile the two.