I have been looking for something exactly like this, Obsidian with a calendar plugin didn't feel right and I don't like that https://reflect.app is online and Apple only. However two immediate gripes

1. The name is kinda forgettable or weird, I installed it this morning and every time I go to pull it up I have to think to remember the app

2. Dark mode is nice and all but some people like myself cannot use it https://jessicaotis.com/academia/never-use-white-text-on-a-b... so consider a light theme or even better a soft palette