I see that Ireland and US-eligible Shane O'Neill is playing for Excelsior (David Connolly's old club) in the Netherlands now: https://www.transfermarkt.com/shane-...spieler/229912
Whilst I was looking up O'Neill, I also happened to come across a 23-year-old Colorado Rapids centre-back named Joseph Farrell: https://www.transfermarkt.com/joseph...spieler/430373
Farrell is US-born, but surely must have Irish roots with a name like that.
Conor Donovan is another player I spotted under the "comparable players" heading on that site (TransferMarkt.com): https://www.transfermarkt.com/conor-...spieler/336166
According to the site, he was born in the US (and played 29 times for their under-17s and ten times for their under-20s) but is also eligible to play for us. He's 22 and presently plays for Rio Grande Valley FC Toros, having previously been with Orlando City.
In an interview with US Soccer, however, he states:
"We are 50 percent Irish and 50 percent Italian. I think I’m more Irish, maybe like 51/49. My mom and dad are from Massachusetts and I think my dad’s side came over from Ireland maybe two generations ago."
If he can only trace his Irish ancestry to great-grandparentage, then he wouldn't actually be eligible, to the best of my knowledge.