The issue is uploading routes to the device when your phone doesn't have any network connection at all.
I think as long as the route can be accessed by the elemnt app (e.g. you've made it in ridewithgps and the elemnt app has some form of network to access the route) you can still Bluetooth it to the device without a WiFi network. This still seems to work on my old elemnt.
I wasn't quite clear there. The issue is in uploading a GPX track (for instance generated offline by OSMAnd when you're lost with no connection) when you don't have a network connection.
I think as long as the route can be accessed by the elemnt app (e.g. you've made it in ridewithgps and the elemnt app has some form of network to access the route) you can still Bluetooth it to the device without a WiFi network. This still seems to work on my old elemnt.