I don't know if the government of any African country have adopted the system of paying salaries in Bitcoin, but I know here is Nigeria they haven't, it's possible to pay employees using Bitcoin or other crypto currencies
That is not even possible since no country in Africa has adopted the use of bitcoin as legal tender yet and if they did, it is not necessary they pay their workers salary in bitcoin because not all of their workers are computer literate that can manage a wallet by themselves. Only Central African Republic have taken a good course in bitcoin and I don’t think they pay their workers salary in bitcoin.
With the services of some crypto currency payroll agencies like Bitwage,papaya global, ontop, which will make it possible for the government to pay their workers in Bitcoin or other crypto currencies and can be sent into their digital wallet,
Since it has to do with the government another agency can be set up in the country in respect to paying salaries as Bitcoin which will somehow help in the growth of the economy of the country.
This is not the most convenient way to help grow the economy of the country and that is why the government is not yet to buy the idea yet. They could see the advantages but are not yet convinced with the disadvantages. As we want full adoption and widespread use of bitcoin, we need to look at the aftermath of it when used for any purpose that will not be convenient for the users since this is a technology that needs to be introduced gradually and users enlightened about it before them agreeing to save or use that currency for their own purposes.