IS there any other airline besides Aer Lingus flying direct to Ireland from the East Coast this summer (2020)?
Delta flies non stop from JFK and Boston. Google flights can show you more options.
Not sure what flight search engine you are using, most folks on this forum recommend google flights or skyscanner. We flew from Philadelphia direct to Dublin on American airlines I believe.
Aer Lingus (many cities), Delta (several), United (a few), American (one) and incredibly, Ethiopian Airlines (just from Dulles).
Several options from Canadian cities in the east as well.
Personally, I liked Aer Lingus a lot.
Norwegian also flies of JFK
A great trick I learned on this forum: to see who flies where from a particular airport, look at the aiport's Wikipedia page.
Here's Dublin airport: https://en.wikipedia.org/wiki/Dublin_Airport#Passenger
and Shannon airport: https://en.wikipedia.org/wiki/Shannon_Airport#Passenger