Despite having more than 2 billion users, WhatsApp takes a long time to implement new functions, although to be fair, so far in 2021 they have announced a few important news such as transcribing voice notes, hiding the last time, or listen to messages before sending them, among others.
However, one of the most important is the multi-device support that is already in beta, an option that for the first time in the history of the service, allows use the desktop app without having to turn on the mobile. But, despite this, the WhatsApp multi-device is still quite limited: only 4 devices and only one device can be mobile, although it seems that not for long.
WhatsApp is working in a true multi-device mode, more similar to Telegram
The folks at WABetaInfo have already detected that WhatsApp is working on improving its current multi-device mode, upon discovering that in the iOS version it is possible to link our account on a second mobile device: on an iPad.
At the moment we are talking about the new app for iPad that WhatsApp will have, and not the stretched app for iPhone. Which implies that that limitation of only one mobile device will be over, something that is also being worked on in Android.
There is no indication that this will be limited to tablets only, so we would be closer to being able to have WhatsApp on more than one smartphone at the same time. What we cannot know for now, is how many mobile devices will be able to have access at the end in total.
Currently we can use WhatsApp on four devices through mobile (one) and the rest can be WhatsApp Web, WhatsApp Desktop (Windows or macOS) and the Facebook Portal. While in services like Telegram these limitations do not exist and we can log in with our account on as many devices as we see fit without ever depending on a primary mobile.