Here are a few finds - you will need to see if they are a fit for your Dominic..

New York Passenger Lists (ancestry):
24 Apr 1905 - Napolitan Prince Ship.
Sarandra, Domenico, age 18, single, labourer, last residence I can't read the town in Italy, destination Buffalo NY, $20 cash, relative Pietro Fabricias (spelling?) at 31 Church Street, Buffalo, NY, in good health.

There was also a Dominico Sarandra, age 26, that arrived in New York on the Friedrich Der Grosse on June 28, 1912, with wife Laura, but from your note it appears the previous one is a better fit.

As you noted 1920 finds them as Sarandrara in Mt Union, Huntingdon Co, with Mary as a widowed head of household, born Italy and states she immigrated in 1913. She is a boarding house keeper, and has children James 7, Olga 6, son Ranasiti? 5, Louie 4, Casper 2 and daughter Arusina? who is 11 months.
Also in the household is a boarder with same last name, I can't interpret first name, but he's a single male, age 23, born Italy, but year of immigration is unknown.
Another board is James Bussiglier, 23 and single, born Italy, year of immigration unknown.
These two boards are most likely some type of relatives.

The WW I draft card dated Sep 12, 1918, shows Dominic Sarandrea, born Nov 8,, 1884, Italian alien, living in Mt Union, PA. His nearest relative is Mary Sarandrea of same address, which you noted would be wife.

There is a Raymond Sarandrea buried on Long Island National Cemetery, born 13 Dec 1914, died 9 Dec 2003, who served in WW II. Enlistment record for a Raymond D Sarandrea born 1914 shows his nativity as Pennsylvania, residence of Queens, NY.

There was a Maria Sarandrea naturalized April 5, 1944, her address was on 11th St, Long Island City, Queens, NY. Her age I beieve was 55.

There is a Social Security index on Maria Sarandrea born 6/15/1888, died 9/1978, last benefit to Brookly, NY, which may be above person.

I'm not sure any of the above is helpful or not, hopefully someone else will jump into this thread and drop some good information.

Good luck with your search, it is definitely a tough one.

Linda