I dont have kids (but may in the future) and one thing I'd like to do before then is get a NAS /plex server and build a kid friendly UI on top of it to keep them off of youtube/netflix/fire tv and greatly limit the content available to them to high quality vetted stuff. Acquiring the content for the server may be its own project in and of itself I admit. I also want to do this for myself too, but I especially want it should I have kids. I'm excited by some of the recent examples of hacking smart TVs too, which seems complimentary.

I just threw infuse logged in as "kids" to Jellyfin which has curated kids stuff - and it's all tied to a custom home assistant timer profile that turns jellyfin access off at a particular time; there's a "door lock" in HomeKit that can be used to extent TV time past the normal cutoff if a parent decides, but since it's a door lock "hey Siri" can lock it, but not unlock it.