That seems like a reasonable interpretation. 5e really emphasizes the vow as an internal source of power, and the impression I get from 3.5 paladins is that their power comes from the lawful-good plane rather than a specific deity. I kinda like the idea that it's an internal power, but then there's stuff like Ravenloft/antimagic/broken vow where they get cut off from it (though those are arguable). I think that kind of internal power is more a monk thing.
But Miko's powers seem to come from, or at least be under the jurisdiction of, the 12 Gods. They
seem to visually step in, and
Soon basically confirms that. I guess that gets into some weird theo-philosophy about what control deities have over the alignment planes they rule over. Particularly in this world's complicated pantheon of non-interference pacts. In typical DND settings I'd speculate that the plane is just an extension of the will of the deities ruling it, so maybe a paladin who manages to *accidentally* wrong enough of those deities could find their powers put on hold. This setting's creation story is pretty unusual so who knows.
This is another low-sleep ramble. I played a lot more 3.5 clerics instead of paladins. They always had a god even though clerics are totally allowed to just channel alignment planes and pick their domains, heh. But when my second cleric got permanently brainscrambled by some alienist things (long story), he became a pretty dangerous DM-run antagonist because he was now channeling *the far realm*, hehe. We had fun setting that up.
...Hehe, I just remembered I sorta pulled an Elan/Nale with my first two characters. My first character was a druid who turned into a horse sometimes. My second character was a true-neutral cleric worshiping Obad-Hai the forest god, always used elemental and healing spells, happened to be a satyr, and deeply resented the first character who he was "totally different" from.
Just reminds me of Nale taking that crazy multiclass rather than being a bard