You will need to prove vaccination and that means fully vaccinated under current proposals. This of course can change. Irelands aviation industry is basically shut down for any meaningful tourism travel and looks likely to remain like that for most of the Summer.
So unless something radically changes with the governments planned announcement next week on a road map to recovery then you need to be aware it may or may not be possible to fly to Ireland. Its hard for someone outside the country to fathom but the US
is pretty much business as normal if you compare to Ireland which is locked down in terms of travel. It remains to be seen what tests you will need into enter and leave the country if the Irish government decides to allow limited amounts of unvaccinated tourists in.
Just to give you an idea it is currently illegal to take a 50 mins flight from Dublin to Heathrow and punishable by a fine of EUR2000 per person !