Seán

Can be pronounced as /ʃæːn̪ˠ/ in the Ulster dialect
https://en.wiktionary.org/wiki/Se%C3%A1n [noted -ed]

The American pronunciation can be debated because people in the USA pronounce things differently depending on what region they are from. I am from New York, my husband is from Idaho, and there are many words we do not pronounce the same; don't even get me started on the south.
"shawn" and "shon" I would probably say the same way if I read it, but I can see with an English accent how you would say these words differently.

The name is pronounced in Irish like the English version Shawn. The acute accent sign over the A is pronounced AW as in pawn, the E is silent because it comes before A.

Pronounced SHAWN. Cripes, everyone knows this. Don't they?.

The name Sean is pronounced SHAWN as shown. I am Irish and this is my brother's name. The line over the letter A is called a fada, which makes the letter long, which sounds in Irish like AW. Notables include Sean O Casey, writer, Sean Kelly, cyclist.

The name is NOT pronounced SHAWN, there is no w sound, rather it is pronounced SHON. Shawn is a different similiar-sounding name, not the same name.

It isn't suggested that theres a w sound in Seán/Shawn. The AW of the pronunciation key is a broad transcription. Basically:

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If you speak like an American and pronounce cot and caught the same way, AW is pronounced /A:/ as in father.

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If you speak like an Englishman and pronounce cot and caught the same way, AW is pronounced /O:/ as in horn.

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If you pronounce cot and caught differently, AW is pronounced /O:/

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Considering that the English call me /SO:n/ and Americans call me /SA:n/, the pronunciation here seems right on. In Ireland though, i could theoretically be called /S&:n/ (SHAN), /Sa:n/ (SHAHN), or /SA:n/ (SHAHN).