Bill, I’m not sure I follow your question. What problem are you trying to solve?
If take a stab and read it as “how could one subscribe to a subset of content from a WordPress website”, then it helps to know that the core functionality of WordPress automatically includes feeds for all the taxonomies (and a variety of combinations) on a site. This means that all your tags, categories, Post Formats, Post Kinds (if you have those) all have individual feeds. Thus if you wanted to separate your “featured” longer reads from your status updates, checkins, likes, or other post types, you could add a specific category or tag to those posts and they’d have a feed you could provide people with to subscribe. If you added “featured” as the tag, then the feed from your site would be:
https://billbennett.co.nz/tag/featured/feed/
Since you’re using post kinds, you already have an “article” feed at: 
https://billbennett.co.nz/kind/article/
All of your top level menu items look like they have feeds associated with them, for example:
https://billbennett.co.nz/telecommunications/feed/
Post Kinds will also allow you to create aggregate feeds based on type so you could provide a linkblog feed of things you’ve liked, favorited, read, and bookmarked (if all of these are enabled on your site) with a link like:
https://billbennett.co.nz/kind/like,favorite,read,bookmark/feed/
It’s a bizarre hodgepodge of both Post Kinds and a category, but you can also specify exotic things like https://boffosocko.com/?kind=note&cat=945 which are things on my sites which are notes and categorized as reads. Simply throw in feed (to the right spot) for https://boffosocko.com/feed/?kind=note&cat=945/ et voilà! Something like this could allow you to tag/categorize your notes, likes, etc. and still not “spam” readers with them because they might be subscribed to your content with the taxonomies of “article” and “telecommunications”, for example.
Some additional illustrative examples include the fact that for most/all of the post kind links on my own homepage one could add /feed/ to the end of those URLs and get a subscribeable feed out of them. I also have some examples on my Subscribe page.
I’ve written a bit about some of this at “Cleaning up feeds, easier social following, and feed readers“, which also includes some links to prior work which may be helpful.
Here’s some additional detail from the WordPress Codex that may be helpful as well: https://wordpress.org/support/article/wordpress-feeds/#finding-your-feed-url