Looks like the same offer is available in the US:
https://www.kobo.com/us/en/p/giftcards
Limited time offer. Receive a bonus $10 eGift when you send a Kobo eGift of $60 or more. Offer good for one time only per customer. Offer starts June 07, 2025 12:01 AM EST and ends June 16, 2025 11:59 PM EST. You will require a Kobo user account to redeem or send an eGift. Bonus eGift will be emailed to the purchasers Kobo account on file within 72 hours after purchasing the eGift. Rakuten Kobo Inc. reserves the right to change or end this offer at any time without notice.