I was looking for someone to mention Magit. It just rocks!

I would recommend the KDE spin of Fedora.

The idea would be:

1. If a top level heading for today’s date doesn’t exist, create it and create a subheading
2. If a top level heading for today’s date does exist, simply just add a subheading.

Take a look at the file+olp+datetree target for the capture templates https://orgmode.org/manual/Template-elements.html

I am not sure how to make it insert an active timestamp though.