I am a big proponent of using specialized apps to do what they are designed to do. Not trying to run task management and calendars in Obsidian, for example. It is also nice to have separate icons for these different areas, rather than having to flip through several different windows of the same app.

I use Obsidian for notes, blogs, and long form writing

Todoist for project and task management

Google calendars/Fantastical for calendar, events, tine blocking, family schedules and shifts, etc.

And I 100% agree with using one system for at least a year to give you a chance to settle into a routine and make it work with as little friction as possible.