"Mythical Historical People".....Isn't this an oxymoron?
The proposition sounds very much like attempts to include Astrology and Phrenology within the fields of science.
We have whole groups of people on wikitree working on providing sources to profiles which have none, i.e. Source-o-Thon. Genealogy is supposed to be about providing proof of one's background instead of legendary profiles which may not have existed at all, at least for wikitree purposes. We don't need that here.
The profiles you are proposing go back well before the Dark Ages. There is no way you can prove any of this stuff except for some books which also deal with fairies and leprechauns. Many cultures, and not just Irish, have "trustworthy" genealogies concocted by nobles and Kings which provide "ironclad" genealogy for those folks straight back to the local Gods. That is not genealogy: it's propaganda and balderdash for Stone Age illiterate peasants.
I am a fan of legends and such, and have stood at the foot of Scotia's grave in Co. Kerry. But please, use your time and our resources to provide sources for REAL people.