Hi there,
A little bit of info for you. I have lived many years in Italy and have a posting "Italian Research" and have helped many people in their research.
First I think the surname is "De Blasi" as nearly all Italian surnames end in a vowel. The birth certificates can be obtained from the "Comune" - Town Hall and not the National Archives. Pescara is a Province with many towns and is in the Region of Umbria. The precise town would be Perugia or one of the towns within the province, but which?
Just in case I had a look at the site "Antenati" and nil.
Secondly at the moment with Italy in lock-down there is no way info can be obtained.
At the moment you are stuck, but when everything has calmed down keep me in mind and I'll will try and help you.
Steve62