As part of changing laws in Europe, Meta now offers the option for you to chat with others using third-party messaging apps that have integrated with WhatsApp and that you choose to turn on.
Note: Chats with third-party apps are only available in select regions and may not be available to you.
I feel sorry for all in the wrong region.


Unfortuantely I only found this German heise news from Feb 2024. But both Signal and Threema won’t lower their security and privacy standards to be interoperable with WhatsApp.