Hi Kevin Enario, I want to help you with this question.
I'm also developing with vue.js and haven't found a solution yet to enable syntax highlight for vue files in Azure repos.
That means officially it is not possible at the moment.
But there is a feature request that exists for a long time. A vote probably won't hurt here.
https://developercommunity.visualstudio.com/t/vue-file-syntax-highlighting/598485
If the problem is solved for you and all questions are answered, I would be happy if you mark the answer as accepted to close the thread.