Sexpressions are syntax for linked lists. You can encode a linked list in other ways and as long as you have a reader and printer for it , you could implement lisp on top of it , and it would be homoiconic.

As a very simple example: replace the () with []

As a slightly more complex example: json. (With support for symbols if necessary but that’s orthogonal—you get the idea)

And from there we can go to: yaml.

Lo: we have a white space sensitive homoiconic language :)