Don’t know. I will tell you what I saw a Zumo do with my microSD card.

On it in the Garmin folder were filies like:
gmapsupp.img
gmapsupp.img.russia
gmapsupp.img.wanderlust.v1
gmapsupp.img.wanderlust.v2
gmapsupp.img.openstreetmap.ukrain

For my GPSMAP 60cx I need a computer to rename a file to gmapsup.img. But on the road I met someone with a Zumo and I advertised for the openstreetmap. We put de card in the Zumo. The Zumo read in all… well except for the openstreet ones. But after that he saw and could choose between all other maps.

You could try.