The first thing you must note is that Nigeria is an Empire of Empires, formed a hundred years to a hundred and fifty years ago when the Benin Empire, Sokoto Caliphate and the remnants of the Bornu Empire were annexed by the British. The south with its ports, commerce and the construction of new factories was highly productive and Christian, but the northern protectorate resisted any attempts at taxation out of nationalist patriotism. This made the northern protectorate more expensive to hold onto for the British than it was to keep it, so they combined the southern and northern protectorate to balance the budget - so creating Nigeria. Not the most exciting of national foundation myths but the smallest of decisions have the largest of impacts.
The Nigerian protectorate would then also expand into neighbouring Kingdoms a bit, meaning Nigeria is a sum of many people with many different histories (some hostile), cultures, races, religion and language.
The four main ethnic groups who do most of the power broking of Nigeria are the Hausa and Fulani (collectively referred to as the Hausa-Fulani), the Yoruba and the Igbo. The Hausa and Fulani used to belong to the Hausa Kingdoms and the Sokoto Caliphate respectively, but after the Fulani led a jihad into the Hausa Kingdoms their people started developing as one much as the Germanic invasion of England led to the Angles and Saxons developing as one.
The Fulani speak pulaar and are mostly nomadic and are organized by caste, amongst the various crafts trades, nobles, foreigners and descendents of slaves. They also follow an honour code of sorts called pulaaku, demanding patience, temperance, discipline, modesty, respect even for enemies, personal responsibility, courage, industriousness and wisdom.
Being the largest nomadic ethnic group in the world they are much under threat from urbanization or conflict with farmers over grazing space for their herds, and fear over time their way of life disappearing like the sands of the Sahel in the wind. The women often have markings on their face given to them when they are children using ink just as the men do, and they sometimes decorate their hair with beads and shells and other things. The Hausa speak the Hausa language and are mostly farmers, traders and crafters, increasingly literate and urbanized, holding onto some influences from pre-Islamic African paganism.
The Hausa-Fulani are both mostly Sunni, with some sizeable Shia minorities or Sunni minority sects like the Salafists, and under the Caliphate rule was semi-feudal under Emirs - this style of governance continued by the British and increased the importance of religious conservatism and the political heads, with the followers more accepting of autocratic rule.
The Yoruba are in contrast to the Hausa-Fulani incredibly urbanized, having complex urban societies centuries before the British arrived, with the cities being ruled by Kings ruling in various degrees of autocracy or power delegation to the tribe's council. The Yoruba are mostly Muslim and Christian and their society allowed for more upwards mobility with the awarding of titles and acquisition of wealth on merit or selection, instead of just hereditary, and about a fifth still follow the traditional Yoruba religion (which I can't do justice as it's not a codified religion founded by one man, rather the sum total collection of all pre-Islamic and pre-Christian Yoruba history, songs and traditional religion).
The Yoruba are defined as one ethnic group by virtue of their shared history, language and culture, but they are a collection of many ethnicities bound together by their shared past. The Igbo developed a form of governance without hereditary monarchs altogether, being ruled by common assemblies and councils of elders. They did not have much of a sense of nationalism as the Benin Empire until after their exposure to Europeans and the other ethnic groups that now make up Nigeria, resulting in the Nigerian civil war where they declared a war for independence against Nigeria itself.
Predominately Christian and being the seaface of Nigeria the Igbo began to make up the mercantile and intellectual elite of Nigeria, sending their children off to British Universities (a tradition that extends till today to elite Western Unis in the USA, UK and Nigeria improving its own domestic education faculties greatly benefited the Igbo in particular as well).
The more liberal Igbo and the Yoruba in the middle led the political struggle for independence from the British Empire whilst the conservative northern Hausa-Fulani wished to protect their political system and culture from political dominance by the intellectually elite south, whilst the British practice for indirect rule through the Emirs guaranteed Christian missionaries could not proselytize on their land and no one would try to centralize power away from them. This would eventually result in civil war after independence, with the Igbo believing they would have Yoruba support against the Hausa-Fulani, but instead the Yoruba and Hausa-Fulani both allied against the Igbo and the British government delivered decisive amounts of heavy weaponry to the Nigerian government to preserve Nigeria.
Heated disputes over oil rights and such continued afterwards in addition to a string of military coups, but today after democratization the three main ethnic groups balance power between them very well and all strive to maintain Nigeria's solidarity, handing Presidency from one of the three to the other to ensure no one group maintains political dominance.
They allow female soldiers in the army and there's a lot of anxiety surrounding their role in frontline combat, particularly after some were abducted in an attack by Boko Haram, otherwise it's legit
So I'd guess your average Nigerian female soldier would be a well-educated Western or Southern Nigerian, possible former officer cadet of the Nigerian army or Police and now Sergeant of XCOM, possibly overcompensating for prejudice faced as a woman by being manly brutal to the max, would be pretty much used to using any weapons from the traditional weapons manufacturers of the USA, Russia (or Soviet stocks), UK, Germany, Israel, France, Sweden e.t.c.
Nigeria doesn't have good domestic arms industry due to corruption