I think it’s just USA. Nowhere else has introduced new tariffs for stuff from Japan to my knowledge.

Edit: Another article that clarifies it is just the US.

https://www.gamespot.com/articles/nintendo-switch-2-preorder-guide-mario-kart-world-bundle/1100-6530531/

Here is the full statement Nintendo sent GameSpot on April 4:

“Pre-orders for Nintendo Switch 2 in the U.S. will not start April 9, 2025 in order to assess the potential impact of tariffs and evolving market conditions. Nintendo will update timing at a later date. The launch date of June 5, 2025 is unchanged.”