Is my travel abroad for work considered an expansion of provision (rizq) and an act of disobedience (ʿuqūq) towards my 67-year-old father, especially given the niqab issue he imposes on me, and despite my sisters being with him, he will be psychologically affected by my distance from him as he has not yet accustomed himself to my absence?

If travel is safe and does not harm the father, then there is no impediment to traveling for work without his permission. The psychological impact, represented by the father's sadness at his son's departure, does not religiously prohibit travel, unless there is a fear of significant harm. Obedience to him is not obligatory in preventing the wife from wearing the niqab, because it is a permissible act, rather obligatory according to the more preponderant opinion. It is advised to be gentle with the father and patient with him.