In Animal Crossing: New Leaf, the Sanrio furniture and clothing items could be ordered when visiting the associated villager’s trailer after scanning in the associated amiibo card. This RV mechanic doesn’t exist in New Horizons though, so we think it’s likely that the Sanrio cards will work similarly to the existing poster system.
When you tap and scan an Animal Crossing amiibo card for the first time to your Nintendo Switch while at Photopia on Harvey’s Island, the associated poster item is unlocked for order in your Nook Shopping’s Special Goods section.
After having been unlocked in Nook Shopping, you can buy these Sanrio items at any time and as many times as you want within the daily catalog order limits, including for trading with other players.
Even the existing Sanrio Posters in Animal Crossing: New Horizons use this system, so we think it’s quite likely that the Sanrio furniture & clothing items will work similarly, likely with their own category tab. That would mean only Sanrio amiibo card owners can order the items directly.