WhatsApp for Huawei Mate 20 Pro

The Mate 20 Pro shipped before Huawei lost Google services, so on the original EMUI build WhatsApp installs normally from the Google Play Store. If Play is missing or broken after a wipe, open AppGallery and use Huawei's Petal Search to fetch the official WhatsApp APK, or download it directly from whatsapp.com/android and allow installs from that source under Settings > Security > More settings > Install apps from external sources. See how others solved this on Reddit

Huawei's aggressive power management is almost always the cause: go to Settings > Battery > App launch, find WhatsApp, switch it from Manage automatically to Manage manually, and enable Auto-launch, Secondary launch and Run in background. Also confirm WhatsApp is up to date and that the phone's date and time are set to automatic, since a wrong clock blocks the connection to WhatsApp's servers. See how others solved this on Reddit

Drive backups need the Google account and Google Play services healthy, so open WhatsApp > Settings > Chats > Chat backup and make sure a Google account is selected and the phone is on Wi-Fi. If it stalls, clear the cache for Google Play services and Google Drive under Settings > Apps, re-add the account, and try again. WhatsApp also keeps a local backup in the phone's WhatsApp/Databases folder, which it restores automatically when you reinstall and verify the same number even if Drive fails. See how others solved this on Reddit

Android-to-iOS WhatsApp transfer can't use the Google Drive backup, so use the official Move to iOS app: set up the iPhone fresh, and when you reach the Apps & Data step choose Move Data from Android, then follow the WhatsApp prompt on the Mate 20 Pro to transfer chats over the temporary Wi-Fi link. Both phones must stay connected the whole time, and it only works during the initial iPhone setup, so do it before fully activating the new phone. See how others solved this on Reddit

For Android-to-Android the simplest route is WhatsApp's own backup: on the Mate 20 Pro open WhatsApp > Settings > Chats > Chat backup and run a fresh Google Drive backup, then on the new phone install WhatsApp, verify the same number, and tap Restore when prompted. If the new phone is a recent Huawei without Google services, instead use WhatsApp's built-in Transfer chats feature or Huawei Phone Clone over local Wi-Fi to carry the chat database across. See how others solved this on Reddit

WhatsApp ties itself to the number you verified, not to which SIM slot is active, so once it's registered you can swap or disable that SIM and still use WhatsApp over any data or Wi-Fi connection. Keep the second travel SIM in the other slot for cheap local data under Settings > Mobile network > SIM management, and WhatsApp will keep working on your original verified number without re-registering. See how others solved this on Reddit