I celebrated too soon. It's been 72 hours and no gift card in sight. Who knows how long this refund will take to arrive. ♀️
Okay - problem solved! Apparently they refunded the entire order to my credit card (even the gift card amount), because I paid for like $2 extra with my credit card. That's kind of nice that my gift card turned into cash somehow.

Dropped off my return on 4/11.
It was picked up by Newgistics on 4/16.
Confirmed as returned by Nordstrom on 4/28.
Refund posted on my credit card on 4/28