I am not sure I am the best to answer about marketing and legal aspects, but I think one thing that is key would be interest worldbuilding around the maps, which usually means at least some writing. Vorropaiah does a great job o this with Elyden. I am not sure the best way to monetize a setting, but the options I have seen have been ttrpg settings, novels, comics, or other games. They all take a lot of work beyond just the world building aspects, but I think ttrpg settings are probably the most doable unless you have an specific interest in one of the others.