Full toot
If you follow any of the #GoToSocial developers you've probably seen this going around already, but 0.17.0 of #GoToSocial will be the first release that includes interaction policies, aka reply-controls.
In the first iteration of this feature, you'll be able to configure your account so that new posts created by you will have an interaction policy set on them, which determines whether your instance drops or accepts replies, likes, and boosts of your posts, depending on the visibility of the post, and whether or not an account trying to interact with you is in your followers/following list.
So for example, you will be able to create Public posts that can only be replied to by your followers and people you follow, or unlisted posts that nobody can reply to or like, etc.
GoToSocial interaction policies will be a superset of other reply control proposals created elsewhere (and already implemented by softwares like Pixelfed and Peertube), so your GoToSocial instance should recognize interaction restrictions set not only by other GoToSocial instances, but by Pixelfed and Peertube as well.
If you're interested in reading about how this will work on a protocol level, you can take a look at the documentation here: https://docs.gotosocial.org/en/latest/federation/posts/#interaction-policy
Please note that this feature is not 100% finished yet, and may be subject to change before release. We're aware of where the headaches and difficulties are, so please don't reply to this post griping about them; we already know (and this instance is still running on 0.16.0 so no interaction policies yet).
Thanks for reading :)
Real question: if you have an unlisted post that nobody can reply to, why would you be posting it on a public service?
That sounds more like the person wants myjournal.txt and less a federated service.
All your followers would see it and sometimes you don't want replies?