Can stores sell and redeem gift cards?

Sell the value now. Ship the shirt when they pick it. Gift cards on any store, sold or issued, redeemable at checkout against the store's catalog. A company buys a hundred for its staff; each person picks their own size and color on their own time. The balance lives on the ledger with everything else, so the cockpit shows what's outstanding and what's been redeemed. Sell them on a public store for the holidays or issue them in bulk as a service award. Partial redemptions carry the remainder forward, and the cockpit reports outstanding balances as a liability you can actually see.

What it used to cost you: Paper certificates and a spreadsheet of who redeemed what.

The feature is called Gift cards. It runs on the same rails as everything else here: one catalog, one price list, one cockpit, your name on the front.