My best friends fiancé asked me to marry them

My best friend of 17 years is getting married. They are doing something really small because of Covid. I figured I would just watch it on zoom because in person they just wanted it to be them, the officiate and the witnesses. I was a little sad I wasn't a witness because we had been friends for so long but its their wedding. Well his fiancé said the reason I'm not a witness is because they want me to marry them and she says it would mean the world to him if I did. I can become an officiate online, and she said they would pay for it. I talked to my best friend about it too and he said it would be the best wedding gift ever. I was so honored. One of my other friends though told me not to do it because I will take all the attention off the bride because everyone will be wondering why the hell one of his female friends is marrying him. That doesn't make a lot of sense to me since everyone in the zoom wedding knows who I am and how long we've been friends. Plus they ask me.