Some great resources already here, so I thought I'd chip in and mention Feedbro, an add-on available on Firefox, Chrome, Vivaldi, and Edge.

It's a RSS feed reader in your browser that doesn't require an account, but if you're kinda weird like me, I mainly use it for finding RSS feeds on web pages then adding them to a separate RSS reader.

With RSS being more & more buried on some sites, this is a super useful tool for finding otherwise hidden RSS feeds imo.