No doubt the cost of labor is a slave wage compared to here. Cost of living is also vastly different. Employee expense is nominal compared to the other things you have to pay for. And if it's an outdoor grow then most of those employees will be seasonal at harvest.
It is not legal to ship weed from another country into the US. Not saying it doesn't happen, or that you can't - just that there will be consequences if caught. When THAT part of it is legal, then the import/export stuff and taxes will make it a non-starter profit-wise. So your market would have to be other than the US for the time being - and maybe forever depending on the tariffs and such.
The cost of living is different in some aspects but everything else is pretty much the same. You have to remember the taxes is also different which makes "cost of living" different.
Even though the cost of living is lower (food is cheaper, and medical care is cheaper) everything else is more expensive and unaffordable for the majority of the African population in their own countries. Ownership of land, housing, rent, cost of water and electricity, municipal tax, income tax, cost of fuel, cost of a vehicle(usually double that what it is in the US), cost of education (it is cheap for a foreigner but expensive for locals).
Also in Africa all forms of growing is done, indoor, outdoor, light dep, greenhouse. It is also not financially feasible to do "seasonal" harvests for corporate companies especially those that is publicly listed (like the company in my previous post) as they want revenue streams that shows quarterly growth for their
disconnected investors. So supplemental lighting is used in times of the year when its needed. You also have a higher rate of success incase something goes wrong its possible to recover losses within 2 grow cycles.
Usually that is how it goes you have 4 harvests a year so one for each quarter which is 3 month cycles of 2-4 weeks veg (from clone dependent on strain), 8 weeks flower, 1-2 week dry, 2-4week cure. Or you can do fresh rosin extraction. Regardless of which direction you go large grow ops is in full perpetual cycles so its non stop.
You also have to look at it this way in the said link I did of that company and the location in Lesotho. Lesotho is run by a monarchy which has strong relations to the British empire and the diamond trading industry. Majority of the population lives in extreme poverty while a few fat cats sit at the top.
It is not as simple as "Investing in Africa" because that investment may be financial support to keep the poor poor and oppressed so you have to ask yourself some difficult questions internally and approach it in a way that makes it possible for you to sleep at night.
Who you partner up with will determine if you are going to succeed short term and disappear, or struggle short term and succeed + be stronger long term.