He's ADHD and the teachers can't cope. There's also no suitable schools in the area.
HAHA I wish could send him to a boarding school!
Sorry, ADHD is no excuse. As an anology, he probably scales quite high on mental acuity, but like a car with a really big engine, no brakes and really tiny wheels... his control suffers.
Home schooling is going to treat the symptom, not the cause and is likely to alienate him even more from society.
It's not the school that must deal with ADHD, it's you the parents.
I wish this binary decision making would go away. It's not either play fortnite or not. If it's not fortnite, it will be something else. Fortnite is a symptom.
What needs to happen is that he needs to be helped to control himself, to reign himself in. One idea I can think of is to film him and make him aware of what he does. Play it back to him.
Also, set up a reward system. He does XYZ and gets rewarded with times of his choosing to play. This will allow him to play at times that his friends do.
When he behaves badly, then remove the privilege and increase the cost of being able to play again.
Above might seem like punishment, but it's not, it's breaking a cycle he needs to learn how to control.
Don't set up a negative feedback system, it does not achieve positive results.
Lastly, revisit the system constantly to see what works as a reward system and what comes across as punishment.
Find ways to remove punishment (negative cycles that fuel rage) and create rewards for self control.
The anger is a symptom. Possibly due to a loss of control in his life, possibly starting with the divorce or loss of previous dad (I cant cover all the bases here).
Fortnite offers a modicum of control because his own actions determine his fate, when he loses control (dies/presses the wrong key) then he also loses control of his anger, because its a trigger.
He's the child here, you need to equip him with brakes and the appropriate size wheels to deal with what the road throws at him.
Externalising the problem isn't going to fix the internal one.
Good luck.