Code and data being equivalent is a consequence of Turing completeness; you can always write a Python interpreter, point it at "data" and have it execute that via interpretation.

> All data is potentially code only in a Von Neumann architecture, but not in a Harvard architecture, where there's a separation of data and code with different memory access to each.

Says you. I wrote a program for a Hardvard architecture chip (PIC) that read bytecode from the data memory and executed it. Updates were made by replacing the data block with a new data block.

In practice, there is no way to separate data and instructions. After all, JS downloaded inside a webpage is literally data, and it gets executed.