Unfortunately and as he stated "I cant use my smartphone because it is faulty".

At the OP, as you requested navigation, note that a number of units can do nav. reasonably well, but about all work best when you use an on-line app on a PC or tablet with WiFi to generate routes. RideWithGPS is a very popular and widely used website, Garmin has their own with Connect, Osmand maps is another and I think allows a smartphone app to generate navigation as well which can then be ported to a device. Of the 2 dedicated GPS units I've used, the Wahoo Bolt or Elemnt have great integration with RWGPS, though I much prefer the maps and navigation of the Garmin 1000 over Wahoo and have good results using the Garmin Connect route (course) generation system.

Nothings cheap though, Garmin 520+ and Wahoo Bolt are in the $250 and up range, Wahoo Elemnt and the Garmin 1000 are in the $320+ range. I think the Edge Explore is now what they used to cal the Touring and a caution as the Touring models got horrible reviews and comments for buggy and poor features. If I had a choice between a Garmin Edge 820 and a 1000 I'd take the 100 as it's larger and that makes viewing maps easier.

As much as I love using my 1000, for everyday use as a business, I might choose the Wahoo Elemnt as the software and support is as good as it gets. But take a good hard look at the different maps and navigation methods of Wahoo vs. Garmin. I know that on Garmin's you can generally read street names on the map, which Wahoo does not offer on their units.