I think that power generation may play a part in Italy's restricted use of aluminum in aircraft construction.
Italy had access to some bauxite - at San Giovanni Rotondo and Olmedo, Sardinia. There was also bauxite in Italian East Africa although I don't know if the Italians were aware of those deposits. Duralumin also requires copper, magnesium, and manganese. The empire could provide those - Eritrea had magnesium and copper, Ethiopia had manganese.
Still, it takes 2.3 tons of bauxite to produce 1 ton of alumina (aluminum oxide) from which a half ton of primary aluminum can be created. Between the wars, effort was expended on transforming the volcanic ash leucite into alumina (by extracting aluminium tectosilicate) - the goal being to make Italy independent of imports.
A huge amount of power is needed to create aluminum - it would take about 8,500 kWh of electricity to produce that half ton of aluminium. Italian annual hydroelectric power generation had risen to about 14,391,000,000 kW by 1937 (about 75% of that from the Alps). But Italian electrical use had also increased dramatically - 1937 useage being about 14 times greater than 1908. A lot of this had to do with the Fascist regime's emphasis on electric trains to reduce emphasis on imported coal.
So, in attempting to solve one problem - excessive coal use requiring imports - Mussolini et al expended surplus energy which might have allowed them to create more aircraft-quality aluminum. Mind you, AFAIK, leucite is still mainly used just to make fertilizers and alum!