Solo founder here, launching Lunelo on June 8. The thing I keep coming back to: I've abandoned every planner I ever used, and it was never the features. It was the pile. 40 open tasks, then 100, then I stop opening the app because it feels like a list of everything I failed to do.
So I built Lunelo around one rule I almost talked myself out of: cap the day at ~5-6 real priorities. Whatever you don't finish just rolls to tomorrow, quietly. No red badges, no "overdue" guilt. Momentum, not a museum of debt.