A diesel generator needs a supply of fuel that can be trivially blockaded as Iran is so successfully doing.

The whole world is suffering from the effects of that disruption.

The supply of diesel itself also requires refineries and they can't be moved or rebuilt quickly either.

Ukraine is doing a sterling job of attacking Russia's refineries. All the portable diesel generators in world won't help you invade another country if you have no fuel to run them and no supply lines.

A small portable balcony setup costing a few hundred dollars, the type sold in supermarkets in Europe, will run every day and keep you alive.

There's nothing the enemy can do about it other than a direct hit and that would take out your generator and fuel anyway.