Well
WinCE CallStack snapshot (function names unknown - map file \storage card\NAVIGON\navigon.map not found
Are you sure that you unlocked the device properly or set the paths correctly?
What tool/shell did you use?

However, as far as I could see, all those older models ran igo 8 exclusively

It certainly doesn't cost anything to try Primo 1.2, this version worked on HP PDAs if I remember correctly:
Spoiler: screenshots
[Only registered and activated users can see links. ]

[Only registered and activated users can see links. ]

Spoiler: download

[Only registered and activated users can see links. ]

This is the minimum package, data.zip only for 480x272 resolution,
Add latest globalcfg, at least one map and possibly a different language