It is totally safe; Ireland has no real history of anti-Semitism.
But it is not the local custom. Jews in Ireland wear wool hats, not yarmulkes. You will stick out like a sore thumb. I wore mine and I did. It advertised me as a tourist.
And you will want the wool hat! It rains every day in Ireland in the summer. It is such a light misty rain that typically you don’t need an umbrella. My trip to Ireland was the only time I have ever missed Kiddush Levanah.
The government is anti-Israel but the people are warm and friendly. I had a Catholic cab driver who could not stop talking about how he was so happy with the Jewish school he sent his daughter to. (Not enough Jewish kids so the one Jewish school takes non Jews as well. It is well-funded by the government.)
No eruv anywhere in Ireland. Not enough Sabbath-observant Jews to justify one. No real kosher restaurants but there was a kosher caterer in Dublin who would send food anywhere in Ireland.
Enjoy!