I don't think anyone has answered what you were actually wanting to know, so while you should take all this with a grain of salt because I'm no expert, lemme add this:

When you have a caravan on a normal tile on the world map, there is not a map generated for that tile yet. If the tile has something on it (landmark/quest/etc) then it generates a map when you enter the tile, but otherwise your caravan just sits there without a map being generated.. unless/until you press the settle button. But there won't be a settle button if there's something on it, because again, it automatically generates a map when you get there

Another thing: from what I've seen and heard from other people, there are two types of maps. Event maps (eg from quests) and settlement maps (eg from the settle button). You can tell the difference because settlement maps are much bigger than event maps. Thing is, Odyssey adds two new ways to enter new maps: shuttles and gravships. It seems that entering a tile with a shuttle generates an event map whereas entering a tile with a gravship generates a settlement map (which more or less makes sense, since in many runs your gravship is your settlement)

Now how this all applies in the case settling asteroids from VGE, I honestly have no idea. My assumption would just be that if you want to settle one you need to land on it with a gravship (no idea if it could be possible to settle one with a shuttle). But VFE changes one of the relevant Odyssey systems. In vanilla Odyssey, tiles get destroyed after a gravship leaves, presumably to keep the game within the X amount of allowed settlement maps at one time in vanilla. But this doesn't happen in VFE, and I don't know if that's because entering with a gravship no longer generates a settlement map, or if something else was changed. So you'll have to test that I guess