How do you acquire the new Harvest Tunic/Dress and Straw Hat?

I know they're meant to be sold by Hildir but she does not currently have them in stock for me. Are they unlocked by returning one of the 3 chests that were stolen from her? Or are they locked behind defeating a certain boss? I can't seem to find any information on this since none of these items have pages yet on the wiki nor are they mentioned on Hildir's page.

For reference, I haven't returned any of her chests yet (though I have the silver and bronze ones at my base) and have only defeated the first 4 bosses. I'm also not using any mods.

EDIT: In case anyone encounters the same problem, I solved it by defeating Brenna and bringing the Brass chest to Hildir. Idk if it has to be the brass chest or if delivering any chest will work.