Is chewing gum outside the home forbidden, disliked, or a matter of etiquette?

Manufacturing chewing gum is permissible and there is no harm in it. However, it might be considered a breach of muru'ah (chivalry/integrity), and this varies according to countries and individuals. What is required of a Muslim is to preserve their muru'ah, which is achieved by avoiding base matters. Chewing gum in front of people in markets is considered a breach of muru'ah in the custom of many countries.