Me and some friends (3 stack) played in an unrated game and was the first game ever that we can confirm we played against a radiant (confirmed by friending player, radiant 170 in NA.) We had a Brimstone that never bought a single ability and his friend (2 stack) confirmed that it was the first game of Valorant he ever played.

So someone in the top 1000 players globally played against someone who has literally never played before. Either unrated MMR is not a thing, or its broken.