I have added MR in upstream with possible pinned posts implementation.
I decided to use
value and its processing now work in the way like I think pinned posts should - it autmatically disables comments and likes so pinned post looks not so attractive for spamming or flooding in comments.
Also at this moment there can be only one pinned post but it is not hard to enable multiple pinning.
Will be happy for code review and suggestions from respected Hubzilla developers. https://framagit.org/hubzilla/core/merge_requests/1792