I was involved in some beta-testing of this app and ,I dare say, this is a good and positive app, with a cool character and short guides to every mood status. Especially I liked breathing practice (it has 9 variants) and self-check tests. What's more, clean ui design also makes my eyes relaxed and keep all stats easily available.

I guess it's really safe cause it's open source, you can make notes on your habits but don't really do that. Its simple. Really fast. Haven't found a way to connect it to notion. In general it's a great app to track you habits. Does its job. Not more, not less.