I believe Garmin maps use OpenStreetMap for the data it dispalys. If so, you need to add your shop to the OSM data, and in some future Garmin map update - it will show up.
Basically yes - if Garmin is using OpenStreetMap data in your region. But you’d have to wait for the map to be updated (once a year) if you want all of the users to see it.
For yourself it’s recommended to download 3rd party OpenStreetMap for Garmin devices:
extract.bbbike.org (you can download only basemap here)
alternativaslibres.org (updated twice a week, you can download basemap with DEM or contour line here)
