Transferring WhatsApp from an iPhone to an Android device can be challenging, and it seems like you have already tried various methods without success. However, there are a few things you can try to resolve this issue:
Make sure both devices have the latest version of WhatsApp installed.
Ensure that the WhatsApp backup on your iPhone is up to date. To do this, open WhatsApp on your iPhone, go to Settings > Chats > Chat Backup, and tap on "Back Up Now."
Check if the backup is stored on iCloud. If it is, you won't be able to transfer it to your Android device. In that case, you will need to create a new backup using Google Drive.
Try transferring the backup manually by copying the WhatsApp folder from your iPhone's internal storage to your Android device's internal storage. You can do this by connecting your iPhone to your computer, copying the WhatsApp folder to your computer, and then transferring it to your Android device using a USB cable.
If none of the above methods work, you can contact WhatsApp support for further assistance. They may be able to help you recover your chat history.
It's worth noting that WhatsApp officially does not support transferring chat history from iPhone to Android, so the process can be tricky. Nonetheless, by trying these steps, you may be able to successfully transfer your WhatsApp chats from your iPhone to your Android device.