Recommendation Mac OS X 10.15 (Catalina) CalDAV-based reminders / tasks app

DISCLAIMER: When upgrading you Mac OS X to Catalina be you will be asked if you want to upgrade to the new which offers a number of nice new features. What it doesn’t say is, that the new does not support CalDAV anymore. Once upgraded there is no way back other than: Downgrade your entire Mac OS X, restart the upgrade and select not to upgrade
Also see:

As I have done the upgrade and don’t want to go through the entire downgrade and reinstall process, I am seeking alternatives. 2Do, Fantastical, BusyCal all seem o.t.t. and are also rather expensive.

Can you recommend any other CalDAV-based Mac reminders / tasks app??

A bit late but I searched all day to find a working solution and for now it seams that Thunderbird + Lightning (integrated extension) works.

Or this solution that I don’t get working would also work for macOS Catalina: