It is possible to download the App from the Virtual Expo page in the official website of Expo 2025 Osaka, Kansai, Japan. You can also search for "Virtual Expo" on various download sites and download it.

▼Downloadable sites
・iOS, iPadOS: App Store
・Android: Google Play Store
・MetaQuest: Meta Horizon Store
・Mac: Official website of Virtual Expo 2025 Osaka, Kansai, Japan.
・Windows: Official website of Virtual Expo 2025 Osaka, Kansai, Japan.

https://www.expo2025.or.jp/en/future-index/virtual/virtual-site/#download