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.
Macros - Macros – Calorie Counter and Meal Planner created and published by JosmanTek for Android and iOS devices.
Habitica - Habitica is a free habit building and productivity application.
Human:Activity tracker - Activity tracker - Walking, running, biking and Calorie tracking
HabitBull - HabitBull
Fitbod - Personalized Strength-Training powered by Machine Learning
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.