How about a “Validate this idea” thread every month?
There are plenty of ideas we work on. It could be useful to have a thread once every month for 'pre-Show HN" stage projects. Just a line or two which describes the project, and maybe a link to screenshots or mockups. You could seek answers on viability, pricing etc.
It has been tried a few times. Sometimes the first edition is interesting, but in the second or third the people run out of ideas. It's usually better to post and discuss each idea in a separate post.
Idea: A Google Keep clone that keeps data in a git repo. You can share todos, notes, pics etc by allowing friends to sync your repos (and by syncing from them).
Data is kept in files as yaml; hence hand editable.
This is doable in the browser as a PWA (via JS git libs) or using native apps. Maybe $1.49/month.