A Munster (southwestern) Irish pronunciation would sound like 'vown' rhyming with 'down'.
It's not Gaelic so why pronounce it.
Gaelic has no letter 'y'.
The word for perfection in Irish is foirfeacht;in Scottish Gaelic it is spelled foirfeachd.
"Gaelic" can mean "Irish Gaelic' or "Scottish Gaelic". They are classified as two distinct languages.
That is not a Scottish Gaelic word. It may be a word in the English dialect of Scotland ("Scots" or "Lallans"). Gaelic has no 'w' or 'y'.
nae-ul
tar-hoil
dhloo-khara
"bawss" (bás)
ain-taha
[món-yair]
djeel-shakht