Students graduate in Nigeria and start spending their working age looking for meaningful jobs. The new graduate gets frustrated even from last level in school thinking about way forward in life. The truth is that, there are jobs. The only problem is that we learn things that are not in high demands.
Over the years, for decades, our curriculum has been same. We have refused to move with the world as a country.
In as much as some of the courses taught many years ago in Nigeria are still relevant, there's need to update the curriculum to incorporate modern realities.
You can imagine that no university in Nigeria is prioritizing cyber security, AI, Bitcoin investment etc. There should be special field that will involve them. Imagine a school with a department called Cyber Security department?

That would be amazing. Sadly these courses are taught only as skills from normal people instead of approved institutions, exposing students to being scammed online and offline by people that'd offer training them in exchange of their money. If there are approved institutions like universities taking these courses as priority, such wouldn't happen.
Our school system in Nigeria is not willing to prepare us for the future, even the present. What they take as priority is creating departments that they can't explain directly where one should work. These departments, you start hearing YOU CAN WORK ANYWHERE from your 100 level, thereby making students already discouraged from beginning of the journey since there's no direct answer to the usefulness of what they are studying.
The major reason for increasing unemployment rate in Nigeria isn't because there are no jobs, but because we focus as a country in training students in fields that are not in high demand. There are courses that you will do, even before graduation, you've landed yourself jobs home and away. Example of such courses are the ones mentioned above. We can't keep training students in fields that when they graduate or even before graduation, they will then start taking other skills to survive because no job for what they studied.
You have spoken well. In some of our Nigerian universities, some of the courses they study their are obsolete and lacks relevance in the labour market. These courses that are not relevant in the labour market should be scrabbed a d incorporate relevant courses into the university curriculum and system. Like you said, their are jobs, as a Nigerian, if you read good course, if you don't work here in Nigeria, you can work abroad. These courses you mentioned are hot cake in the labour market, if go online for job search you will see many vacancies on cyber security, Robotics, and Blockchain. This courses are not studied in our Nigerian universities and those who are opportune to study some of these courses either through online studies are here in Nigeria but are working abroad.
When I was in the university, I studied civil engineering but I studied plenty of the management courses, they want you to learn all the courses so that you can work anywhere, this is actually a wrong way of studying because their is no way you can know everything. By right, a student should only concentrate on his field of study and should not combine other courses to his main area of study, doing that can confuse a student and make your concentration divided.
Another vital thing that most our Nigerian universities lack is good practical, our Nigerian universities should prioritize practical, more especially the engineering students. Here in Nigeria, students will graduate from engineering department but does not have the full practical knowledge of the course that he or she read, is actually wrong.
If our government have the progress and the development of this country Nigeria at heart, they have to look into all these things and incorporate good courses into our Nigerian universities, doing this will help us develop in technologies, produce graduates of international standard from Nigeria.