Let me put it this way: you can tinker in your garage for years, and tack together a car from pieces you bought at junkyard sales… Will it run? Sure. Will it carry 2-4 people? Probably. Can you use it to get from point A to B? Yeah. But will it be the fastest, most fuel-efficient and overly-designed thing of beauty on the market? Hell no.
The tricky thing with plagues is, in the hypothetical scenario of wanting to wipe out as many people as possible, you want it to do just that: wipe out as many people as possible. And for it to do that, you gotta layer it together like an onion. Layer upon layer of fail-safes, kill-switches, activation sequences, chimeric frameworks, biomolecular deterrents, etc. etc. etc. Shit's not easy if you want it to over-perform. And you do. After all, why half-ass the project?
Ergo, you're looking at 10+ years of formal schooling.
And then another 5-10 of tinkering. By yourself. Alone. In secret.
Your plague-baby needs to be built like an onion, because the moment everyone realizes it's a global threat (and if you designed it well, it would be!), then it's only a matter of time until they crack it. So your cute little bug is living on borrowed time, doing its best to kill as many as possible, while every country on the planet fields an army of scientists and supercomputers in an effort to produce a working antidote. It's laughable imagining Africa trying to do anything on this front, but you can be sure all the developed nations would instantly mobilize to end the threat.
That's why I wrote in an earlier post that the hypothetical bug would need to lay low. It would have to be assembled to stay undetectable and dormant until it reaches close to 99% global penetration. Everyone would need to be infected, but without knowing it. Then the bug's kill-switch triggers and its acquisition protocols kick in, killing all darkies in under 24h while leaving whites untouched. You can make compromises (lower lethality, slower transmission, wider activation interval, etc.) but each of them reduces the time it'll take the world to crack it. The only thing the bug has going for it is its layered defense, which, to use the onion analogy again, extends its effective killing power with each layer that needs to be peeled away to produce a working solution.
And you can't achieve that kind of engineered perfection by tinkering around on your own. You need a formal education.
All of this is definitely doable, but would require a high amount of work and iteration, and an ungodly amount of skill.
In a way, it would be like producing Beethoven's 5th. Papa Nurgle's very own symphony of annihilation.
It's an interesting thought experiment, but I doubt anyone with the necessary skill would tackle it.
Virtue-signaling and taking selfies while doing charity work in Africa yields incomparably more social capital, and at a fraction of the effort.