It did suggest itself. There's an
Alwyn too :)
I've only ever met people with the
Anwen spelling, but the birth records show quite a few Annwen births (from 1913 onwards; use of both names seems to be fairly modern) and it's not uncommon for name-spelling to be flexible, or for new ones to be invented, even. It might be influenced by annwyl ('dear').
I'd think of Annwn too - but there are several spellings of that, too! And in some versions, the Otherworld is a lovely place.