Lyra made a website on YouTube uploaded a video detailing the secrets and history of Unown in the games. Except there are no secrets really. You’ll only need a spare 10 minutes to watch this and it’s a shame there’s not much more to them besides being shaped like letters and knowing Hidden Power.
But I recommend you check out the trivia section for Unown on Bulbapedia as there’s some cool stuff on there.
