As an American you can buy us-etf like schwab dividend (schd) or Vanguard s&p500 (VOO), maybe a NASDAQ (QQQ). And you can pay your taxes (only) in the US.
To buy ETF's from Ireland is not bad at all. They don't tax. So you can pay your standard taxes in the US.
For the Rest of the world it is useful to filter taxes through an Ireland ETF to save some money before they have to pay finally taxes in their own country.