This is a little late, but - I do pick and choose which items to preview ahead of time and which ones to keep a secret until release day. Usually former is for QoL features and mechanical updates, primarily with the goal of indicating that I'm working on something that's been requested a lot.
For everything else, not showing previews lets me change plans if something doesn't work out in the course of producing it, or if I decide to swap stuff around based on what people seem to want more. It's what's most comfortable and takes a lot of pressure off of me (not making promises = no expectations when they're released)! I can tune how often I share previews based on knowing some people like the previews though.
Said previews usually go on the Discord #changelog-and-plans channel when they are available. I could also make a thread for them, but I can see myself forgetting it exists after like, 5 days haha.