Is there a sin on someone who is unable to advise non-mahram men in the street, or women, for fear of embarrassment and rejection, despite wishing to advise for the sake of Allah?

If a woman adheres to Islamic guidelines, there is no harm in her enjoining men from evil, provided she is reasonably certain of her safety from temptation and that a benefit will be achieved. If there is a man who can do so, she should entrust the matter to him; otherwise, the situation should be assessed. She must strive to call and enjoin women from evil, and not abandon this duty under the pretext of shyness, unless there is a valid fear. If she knows they will not accept advice, scholars differ as to whether it is obligatory or merely recommended for her to enjoin them.