I’ve lived in Ireland all my life and don’t know Ruadhs or Ruas of either sex. As the figures below show, it’s only started being used as a given name recently.
In 2024, 36 baby boys were called Ruadh in Ireland, up from 4 in 2014. The name was not included in stats before that as “due to confidentiality reasons, a name must be recorded 3 or more times in any year to be included”. It’s not listed at all for girls (though there still may be 1 or 2 a year of course).
In 2024, 13 baby boys were called Rua; the name was not included in stats before 2008, high point of 18 in 2021.
In 2024, 11 baby girls were called Rua, up from 4 in 2018, not included before that.
However Rua (‘Red’) was commonly used in the past as a nickname or identifier added to a given name because of a person’s hair colour.
For example, Eoghan Rua Ó Súilleabháin (Owen Roe/Red Owen O’Sullivan) was an 18th century Irish poet. Dòmhnall Ruadh Chorùna (Red Donald of Coruna), was a Scottish Gaelic bard, stonemason, and veteran of the First World War.