Offline moving map software

I always used NAVIT on a Linux laptop, and was quite happy with it; but it seems to have very little support recently. I installed it on a new laptop and it came up with some weirdo error message (“error:navit:traffic_new:wrong type ‘null’”), for which no explanations could be found, let alone a solution.

What to use instead? Requirements are the ability to run off-line, so map data for all of Europe must be downloadable in an easy way (which was getting harder and harder too, for navit), and get location info from a usb-connected GNSS receiver, probably through gpsd.

Any suggestions? I did consult but found only confusion.

(nb apologies if the question was asked before, or if posted in an incorrect sub-section)

The issue with Navit was solved after I reported the issue on the relevant github page.
There do seem to be few alternatives for navit! I consider joining that team after retirement, they are obviously understaffed.