Tolkien was a far-reaching linguist and scholar who was as inspired by the Finnish national movement as anything else. Early on, he found inspiration in the Finnish poem, the Kalevala, and the heroic folklore it encapsulated. Tolkien studied Germanic languages and historic texts, but he also drew inspiration from Celtic literature and folklore, particularly from Welsh sources.

Tolkien's scholarship was emerging at a time when oral tradition was linked with the nationalist movements of Finland, Norway, Iceland, and as you say, Ireland, but folklore was also at the heart of the "national" cultural movements of Scotland, Wales, Cornwall, and even places like Sweden, Denmark, and Germany, places that were either already sovereign nations or places that sought to bolster their own, unique cultural identities. Tolkien found inspiration in both these contexts - with nationalist movements and ones that captured the strength of a cultural "mythos". He was certainly aware of how important oral tradition could be for those people who sought their own sovereignty, seeking to be self-governing people, but it seems fair to say that Tolkien was seeking to fill a cultural gap that he felt was not being adequately addressed in twentieth century England.

The recent publication, Catherine McIlwaine, ed., Tolkien: Maker of Middle-Earth, produced by the Bodleain in 2018 in conjunction with the library's exhibit of the same name, includes essays for several authorities, many of whom address the complexity of this subject.