Lists are exactly what you described here
Make a list and then you can set it to public or private (if you want others to be able to follow it)
Then you manually add users to the list and then you can use the list selector at the top of the feed to see threads from users only in that list
Perfect!
TBH I have never used Lists.
Wild to hear it but I know that it's hyper underutilized
People just don't know about it. It's super handy. You can even set them as default displays so when you visit the homepage, it defaults to a list you created