Latest Nuvi 1490 LMT maps update (CN Europe NT 2025.10) seems to be incomplete

What map is shown when you look in Settings? 

Did you mean Settings -> Map -> Information?

CN Europe NT 2025.10
[1] Update ALL East
[2] Update ALL West

The neighbouring countries do have some larger towns shown, and some faux highways are displayed that only vaguely resemble the actual highway. There are funny features on those faux highways, like 90 degree turns. :-) But there are no roads that would connect the towns to the "highway". This real road network from my home country end up exactly at the borders.

Both maps I assume are selected? If so have you tried a master reset of your nuvi? That normally resolves any issues after a device update.

There is only one checkbox at the level of the "CN Europe NT 2025.10", the lines below it are just text lines as you can see, no checkboxes.

How do I master reset the device, please? I never needed to know...

Allright, this helped and it solved my problems up to this point, thank you very much, I didn't want to abandon a working device, even though it's somewhat dated to current standards. However, now I have another problem - the backup of favorites (made 2 weeks ago) does not return my favorites when I restore the backup from Express.
I did find the "Import Routes" in My Data in Tools, and the routes imported. The routes consisted of some of my favorites, and their names are displayed when I want to edit a route. But my Favorites list is empty.

Do I just rewrite the Current.gpx with the GarminExpressImport.gpx?

You could try. The important thing is not to rename it current.gpx,  just any other name will do.  The file current.gpx is written by your device but never read by it.

I did it! Thank you very much so far!!!! The device did not really care about GarminExpressImport.gpx, but when I made a copy of that under the name of "12345.gpx", the old favorites/groups appeared on following start (is the software limited to recognizing 8.3 filenames? ).

Now the last thing that is not working like before anymore is the car symbol. It's just an aesthetic thing. If I turn the default car into this blue tetrahedron, I get the car again after restart. Even though before restart I view the map and see the blue tetrahedron.

Glad it's mostly resolved. As the icon is outside the scope of this forum about Express I'll close comments. You could try here for help with that http://www.poi-factory.com/