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 ,
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.
You must be a big dreamer, my friend. First, Bitcoin is not a legal tender in the country, the central government must approve it after it has been successfully passed by the national assembly before such happens. Secondly, it will be an option for staff and not by force simply because they must agree with some terms if they would be paid in Bitcoin as Bitcoin is a volatile asset, which means that most of the staff will not receive the amount they were supposed to be paid. At times, it will be higher and at times it could be lower and devastating, so it will be impossible for the government to force it on people.
The workers also have the right to take the government to court if they are adamant about it as they are entitled to have to get paid for what they worked for. Thirdly, this is meaningless to the economy as it is, what if the workers agree to it and the citizens of Nigeria disagree? I mean the market sellers and all the people where the workers will spend it disallowed it? It will only amount to waste as the workers will quickly be changing it to fiat so that they can be able to spend it. Lastly, have you thought about the higher fees that the government and the staff will part ways with in the name of Bitcoin? In Nigeria, a few dollars is a big money due to the economy and bad FX. Imagine this time when the average fee to send Bitcoin is about $5, which is huge in the country, this can't be a good idea that could replace the almost no-fee transactions they receive their money with and are used to. There are many other factors to discourage this view of yours but let's leave it to this for now.