Definitely a hen. This whole thread prompted me to look again at the Metzer page for appleyards, which is where I got them from.
"We do not recommend our Silver Appleyard for show purposes as we are starting to get females developing dark bills. We are selecting for breed standard and aim to improve this trait in our 2025 breeders."
https://www.metzerfarms.com/silver-appleyard-ducks.html
I do also have a Welsh Harlequin from metzer, those two girls are pretty distinct apart from the bills.
All that to say, I'm not denying that she could be from a more diluted or mixed stock. Not that it really matters to me.