You're saying the moon can be fetched, it sounds like

One console keymap is 2kb, and the X internals to load it were a few hundred kb smaller than the xkb internals. I think it would be a lot of work to get the xkb option to even within 500kb of the console one, and that is still not size-competitive.

If you mean to skip console keymaps entirely, then that's additional size in the form of cxkb (btw google doesn't find it, so I couldn't measure it).