Just to conclude this in case somebody finds it one day.
In short, it is impossible. WA does not support import of its own Exported data
You can probably do it for the entire app (there is a procedure whereby you uninstall the app, thus dumping all data, and then import the zipfile) but not for a specific conversation.
I have easily Exported the conversation from the Iphone to a zipfile. This zipfile now resides on the Android (14) phone.
The next step – importing a conversation into WA from a zipfile – is a mystery. There is a ton of stuff on google but none of it works. All of it refers to a directory called Whatsapp in “the root folder” (which of course isn’t actually a root folder, and anyway this is not a rooted device) which is shown in screenshots to be the same directory as the one in which e.g. DCIM is seen. But the Whatsapp directory does not exist in that location, or anywhere else I can find, on either android 12 or android 14.
The zipfile content is obvious. It is the text of the chat (as a simple .txt file) and then the media (mostly .jpg). But how does one import it? The web is packed with clickbait offering various import tools but none work, and some require you to uninstall WA first (suggesting that they are for a fresh phone where you are importing everything new.
So while it would be easy enough to just dump the media into the Media directory, it won’t get linked into the database to form the conversation, and there is nowhere to drop the .txt file which contains the text.
As an aside, it’s really stupid to be encrypting the text when not encrypting the media but I guess nobody has realised this yet
I think there is actually no way to import the Export file. Best one can achieve is some viewer and there is a number of them online, some as JS and some even online but all ones I found do just the text. The text contains links to media files so it would be fairly trivial to add those but he strips off the text lines containing the links.