I recently purchased an OSM of North America for $13. I followed the instructions on the download and all seems fine although I have not tested the map in the real world.
This got me curious and I found all of this. I am trying to download a map of the entire US just to see if I can obtain the maps on my own but when I try I get a message that my map is too big.
One does not imply the other. OSM if free as in “free speech”, but a product built on OSM data may not necessarily be free as in “free beer”. It’s entirely possible that someone could create a custom Garmin map using OSM data and choose to charge for the use of that product.
That being said, there are enough free OSM-based Garmin map options that you should be able to find one you like that you don’t have to pay for.
The map that I purchased was for North America but there were others for other parts of the world. It is an active Ebay site. I would put the link in but I suspect that would be against the rules. An Ebay search of Garmin Maps will take you there. The current price for the North America version is $14.50.
Believe me I am not pushing this because I too prefer “free” but you folks seem curious about it.