Well, the modern wonder device for the wrist would be an Apple Watch of recent vintage.

The downside* would be that it really wants to be paired with an iPhone. Mostly for the initial configuration , but also so it can use the iPhone as a liaison to the internet.

* Of course it will also cost Apple Watch prices, and the rechargeable battery will begin to fade in a few years

Upsides would include not only a wide array of Watch apps, both built-in and from the App Store. But many of the apps can be voice invoked and/or controlled. Having a live GPS full-on map app on one’s wrist seems like living in the future.

Many iPhone apps automatically sense when a Watch is configured so the iPhone alerts can appear on the Watch, and often the iPhone app can be responded to using the Watch.

For those that are iPhone allergic, I am unaware of the state of things for non-Apple wrists.