Traditionally your WhatsApp backup occurs at 2 am every morning as an encrypted file on your device. If you have set it up, you will find your backup in your google folder drive.google.com, go to settings gear and open settings – select managing Apps option.
Should you be using iOS one of the default settings will be iCloud backup. You can also choose to backup to your Mac/ laptop.
None of the above options are available when migrating from iOS or Andriod to HMS. This may be a bit of an inconvenience especially if there are chats you cannot lose in the transition.
There are several options you can use get your WhatsApp from one service to the next. Some require you to email chats to yourself one at a time and then upload email comms to dashboard then on to the new device. Impossible if you have a busy chat profile.
The most efficient method I found is Mobile Trans Installer. Most people will not have heard about it, very little has been done to market the app and virtually no literature exists on it. It is however the best tool on the market, extremely easy to use and works across all mobile platforms.
Download Mobile Trans Installer to your desktop and install. When complete, Mobile Trans will ask from which device to copy and to which to install WhatsApp. Select the devices as required (your computer will need to have 2 USB ports for this to be successful).
It took 40 minutes to copy 6 years of chats from mu iPhone to my HMS device.
The package will cost you US$35! It is a huge jump for most but will be well worth it.
Please note once you have WhatsApp on your HMS device, you backups will no longer go to your cloud services. They will be saved on your device at 2.00 am daily and backed up periodically to you Huawei Cloud account.