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The recently released Garmin Fenix 6 Pro is in my opinion the best outdoor watch and comes with the free "TopoActive" card.
This map is - in my opinion - based on OSM (OpenStreetMap), but it lacks details and does not fit the high standard of such a high quality watch. In addition, the map is limited, not even Crete is included.
If you want to have a more detailed map for the Alps on the Fenix, you can also buy the TOPO TransAlpine+ PRO from Garmin for ~ 150 €, but I advise against it, because this map contains the same absurd errors as the maps from Outdooractive.
Paths lead in canyons, do not exist, the actual paths are missing, an impudence to charge money for them. The mistakes are so ridiculously obvious, for example, paths lead 30m past the summit (front solstice pass).
Paths have been straightened with a ruler or wind their way through the landscape like a sine curve and can never have existed as one can easily see on the spot or on aerial photographs.
In places, paths lead through buildings or run exactly on slopes, for example west of the Oberföhring Volunteer Fire Brigade. The fact that this error can also be found in Google Maps doesn't make it any better, but you can't plan a bike tour with this map in the city.
In my opinion this is not only true for Garmin, but also for Outdooractive. Unfortunately, these are the only maps I know of (and which can be used in planning software) with a slope gradient layer, which is very useful for planning tours in the snow in winter. Since I bought the maps for the winter, because you can't see the trails when there is a lot of snow, this is especially annoying, if not dangerous for me.
I called the support of Garmin about these map errors in the TOPO TransAlpine+ PRO, they insisted that the TOPO TransAlpine+ PRO is based on OSM, but that can't be true, because you won't find trails in OSM, in my opinion official map material is used, that was the statement of Outdooractive to me, when I asked for correction many years ago. They also told me that they would not correct the mistakes because of that.
To make this clear once again: The mentioned errors are not to be found in the TopoActive map of Garmin, because it uses the clearly better map material of OpenStreetMap, but in a reduced version.
A very good alternative to the maps available at Garmin is the OSM-based map from www.freizeitkarte-osm.de, which I recommend, with a small adjustment, for the Garmin Fenix 6.