JSFiddle - React, Tailwind, and code Playground

HTML

<ul data-group="Companies">
  <li data-company="Microsoft"></li>
  <li data-company="Microsoft"></li>
  <li data-company="Google"></li>
  <li data-company ="Facebook"></li>
</ul>

JavaScript

// All elements with data-company="Microsoft" below "Companies"
let a = document.querySelectorAll("[data-group='Companies'] [data-company='Microsoft']"); 

// All elements with data-company!="Microsoft" below "Companies"
let b = document.querySelectorAll("[data-group='Companies'] :not([data-company='Microsoft'])"); 


console.log(a,b);