Global Variables addition outside functions - Getting NaN 'number'

Question

So I'm using 2 JavaScript functions fetching data from 2 different sources.

function fetchOpenSea() {
    fetch('https://api.opensea.io/api/v1/collection/galacticaliensocialclub/stats?format=json')
      .then(response => {
        return response.json();
      })
      .then(data => {
        var volumeOs = data.stats.total_volume
        window.volumeOsRounded = (volumeOs).toFixed(1);
        document.querySelector('#volumeOs').innerHTML = window.volumeOsRounded;
      });
  }
fetchOpenSea();

function fetchLooksRare() {
    fetch('https://api.looksrare.org/api/v1/collections/stats?address=0x33fd4167e51a10d19c89c3a606389d0fddc3e676')
      .then(response => {
        return response.json();
      })
      .then(data => {
        var volumeLr = data.data.volumeAll;
        window.volumeLrRounded = (volumeLr / 1000000000000000000).toFixed(4);
        document.querySelector('#volumeLr').innerHTML = window.volumeLrRounded;
      });
  }
fetchLooksRare();

I've declared 2 global variables using "window." in both functions, but I can't find a way to addition them properly outside the functions.

function addOsLr() {
  let o = window.volumeOsRounded;
  o = parseFloat(o);
  let p = window.volumeLrRounded;
  p = parseFloat(p);
  let q = o + p;
  document.querySelector('#volumeTotal').innerHTML = q;
  console.log(q, typeof q); // Getting "NaN 'number'"
}
addOsLr();
console.log(window); // Both volumeOsRounded and volumeLrRounded are there as strings for some reason