I was so exasperated by many misleading articles and answers that I wrote my own RSS reader:https://gouessej.wordpress.com/2020/06/28/comment-creer-un-lecteur-rss-en-javascript-how-to-create-a-rss-reader-in-javascript/
You can use AJAX requests to fetch the RSS files but it will work if and only if you use a CORS proxy. I'll try to write my own CORS proxy to give you a more robust solution. In the meantime, it works, I deployed it on my server under Debian Linux.
My solution doesn't use JQuery, I use only plain Javascript standard APIs with no third party libraries and it's supposed to work even with Microsoft Internet Explorer 11.