The cheapest offer on the Microsoft gift-card page is not a Microsoft Store gift card. It is Office 365 Pro Plus for 5 devices with 100GB cloud for 1 year.

What you get:

• Office 365 Pro Plus
• 5 devices, 100GB cloud, 1 year
• Windows, Android, iOS, and macOS as stated on the offer

Delivery: after payment, the code or access details are sent to you by message.