For me, not needing another app and the fact that is easily selfhosted is great. For Obsidian you have to pay for their sync solution and I remember the logseq app was cumbersome and the web client wasn't so good, but that's my opinion.
I've been using silverbullet for a while. Selfhosted, saves everything on simple markdown files and easy to customize with plugins and space scripts.
I use QuickWeather and use the Open-Meteo integration. You can even selfhost it for better privacy probably.
If you want to continue in the same function you'll need to use async/await. In your case:
async function yourFunctionName(){
// previous logic
const myVar = await fetch("myFile.json")
.then(res => res.json());
console.log(myVar);
//rest of code executes...
}
Realize that you have to add async to your function and await to your fetch call. Also take into account that if your function returns anything, it'll now return a Promise instead.