It is definitely in the Munster dialect as is indicated by the title of the book this comes from.

It's possible that as the strong dental velarised n became the norm for broad in all context, words like 'nó' and 'trathnóna' became 'nú' and 'trathnúna' as it is easier to articulate that way

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__̴ı̴̴̡̡̡ ̡͌l̡̡̡ ̡͌l̡*̡̡ ̴̡ı̴̴̡ ̡̡͡|̲̲̲͡͡͡ ̲▫̲͡ ̲̲̲͡͡π̲̲͡͡ ̲̲͡▫̲̲͡͡ ̲|̡̡̡ ̡ ̴̡ı̴̡̡ ̡͌l̡̡̡̡.___

Yeah, nó is pronounced nú in Munster.

I've read that book before Franc, so any questions just ask.

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The dialect I use is Cork Irish.
Ar sgáth a chéile a mhairid na daoine, lag agus láidir, uasal is íseal

I gConamara freisin.