More linked devices are on the table (and the Android tablet) 
signal.org

The latest update for Signal Android [8.20] introduces comprehensive support for linked devices. Now you can easily link another Android phone or Android tablet to your Signal account. […]

We’re also expanding linked device support on iOS [in version 8.22] so you can link an iPhone to your Signal account in addition to our ongoing support for iPads.

A few weeks ago, I went the opposite direction — I stripped messaging apps down to just my phone. It’s part of a personal experiment to steer conversations toward channels I find better suited for urgent matters (phone calls) or more complex discussions (email). That said, it’s still great to see the Signal team cross another item off the never-ending wishlist of features people keep asking for in messaging apps.