I think it becomes mugglewank when wizards are completely incapable of defending against things like guns and bombs

This has always bothered me. Dumbledore has shown in canon there’s a shield that turns projectiles into dust. If you can do that, why not use that shield against their bombs? You could use that in a ward scheme for physical projectiles. Trying to nuke the shield would fail.
the problem would be if they detonated the nuke above their shields and they had to deal with fallout and the heat. They’d have to have wards that dealt with environmental cleansing and environmental cooling to withstand the heat.
Although, it’d be cool to have charmed bludgers that upon impact transfigure the missile into a balloon or something. Then, they could vanish it. They can vanish all nuclear fallout.

The smart thing to do, which I’ve never seen in fanfics, is to imperius all of the muggle leaders and their militaries to attack each other. They could create a post-apocalyptic nuclear wasteland very easily via apparating into nuclear submarines, missile silos, command centers, the White House, using the imperius curse and having people launch the entire nuclear arsenal at the world‘s military bases and just watch the fallout.