I updated my RSS feeds so that you can filter content by tag. So if you only want to follow a specific topic of mine, you can simply append ?tag=tag-name at the end of any of my RSS URLs, and it will only show content with that tag.
Example: https://www.alexstandiford.com/rss.xml?tag=WordPress
Eventually, I'll actually embed this into the interface to make it a little easier to use, but for now this will do just fine ????.