Do changing names and fathers' names for the sake of travel and earning a livelihood fall under the warning mentioned in the Hadith: "Whoever knowingly attributes himself to other than his father, Paradise is forbidden for him," and what is the ruling on nationalities from an Islamic perspective?

Originally, it is permissible to change names in pursuit of a good name. It may even be obligatory if the name contradicts the Islamic creed, such as "Abd al-Masih" (slave of the Messiah). This permission from the Shari'ah is considered an improvement (tahseeniyyat) and is all the more permissible if one is compelled to do so, provided it does not lead to a forbidden act in Shari'ah, such as traveling to non-Muslim countries with the intention of residing there, or claiming lineage from other than one's father. As for Islam's stance on nationalities, Allah the Almighty says: "Indeed, the most noble of you in the sight of Allah is the most righteous of you." Thus, there is no pride in nationality at the expense of piety. One must abandon the claims of Jahiliyyah (ignorance) that divide Muslims, for belonging to a country or tribe is for acquaintance, not for boasting.