I use Libretube as my kids' YouTube app. It uses piped instances to stream the videos, and you can pick the instance that works best for you. I'm wondering if there are any Instances that can be used to totally block all NSFW searches, thumbnails, and videos. Do you know of any other apps, ways, or ideas to make YouTube safer for kids? Let me know in the comments!
You do not have to wait for the app to be released on the Play Store; you can get it from GitHub.