How can I restore the whatsapp chat from android

You can’t. WhatsApp does not support transferring chat between platforms. You can find details here→https://whatsapp.com/faq

I have no idea what 3rd party apps can do, but WhatsApp says there is no way to do it. That’s all I have to go by.

Sorry, WhatsApp does not support to use a backup created with your Android device and restore that info on your iPhone

Does this mean that none of the 3rd party apps that say they will do this won't be able to do it?

I'm also in the situation where I want to tansfer WhatsApp from Android to iPhone. It's crazy if it can't be done.

No matter how important it is, it is impossible, because WhatsApp does not allow a backup from an Android device to be restored to an iPhone.