Without shoes 'ON'
Zonder schoenen 'AAN'
It is possible to add aan in Dutch, but this usually is left out, this doesn't change the meaning.
In British English we would say 'without shoes' rather than 'without shoes on'.
In Belgian Dutch, lopen means to run. To walk is translated as wandelen or stappen
How about "Het model loopt met geen schoenen"?
Why is the article 'het' when work titles are generally 'de'?
Is "Het model loopt er zonder schoenen" too wrong, or kinda strange?
You could add 'er' to emphasize that the model was walking without shoes right now. If you were pointing it out to someone who was already aware the model was walking, you'd leave 'er' out.