At this time in a country like Nigeria, having one source of income isn't enough to cater to 90% of Nigerians needs. In fact, earning in naira is almost of no significance as prices of goods and commodities (especially food items) have been on the high side in recent times and there is no increase in workers' pay. Hence, the need to have other sources of income (especially dollar income source) to enable you to survive financially well in a country like Nigeria.
A typical example of a profitable side hustle to start earning in dollars right from Nigeria is freelancing. Freelancing is simply an online business model that involves turning skills into cash. It involves doing jobs for other people around the world according to a particular skill set that you have. These skills are not usually very technical skills, they range from graphics design, writing, translating, beat production, making jingles, dancing, and even some too simple skills tagged as "no skills". The best thing about freelancing is that it can easily be started by anyone anywhere in the world without a need for writing application letters to get jobs done and get paid in foreign currencies (mostly in dollars).

Freelancing is a gold mine and has changed lots of people lives worldwide (Nigerians inclusive) but many Nigerians are yet to take hold of this opportunity to be financially stable and the good news is that it's not too late to get started especially under the guidance of a fellow Nigerian freelancer.

Go here: https://freelancingsuccess.gr8.com/ to learn more about this lifechanging side hustle.