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.
Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
Habitica - Habitica is a free habit building and productivity application.
ioBroker - flexible and modular application for the IoT and Smarthome
HabitBull - HabitBull
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.