Can you maybe just use your phone? Because the routing on these devices themselves kinda sucks, for all i know. For phones there are really good routing apps though, like osmand for example. Love that app. On android you can also make it work with the fantastic profiles from brouter.

Works in airplane mode, can show all kinds of points of interest, like drinking water, picnic tables, everything really that is available in openstreetmaps data.

The usefulness of course will depend on the osm data quality of where you are cycling.

The ui is kinda quirky but it’s a really powerful app.