Re: I solved this when I was eight
"No one has ever used those pronunciations."
What you've demonstrated is that writing stuff out phonetically in a way that normal people can read (because not everybody is familiar with IPA) is...actually quite difficult.
I've heard "s-cone" (rhymes with blown). I've also heard "skun" (rhymes with stun). And as you mention it, there's also "skon" (rhymes with gone). Origins? Perhaps regional. Tea rooms in the Cotswolds, and also around Bodmin/Padstow.