Here's a few places to start: https://github.com/alainm23/planner https://github.com/alainm23/planner https://apps.gnome.org/Calendar/ https://apps.gnome.org/

Here's a few places to start: https://github.com/alainm23/planner https://github.com/alainm23/planner https://apps.gnome.org/Calendar/ https://apps.gnome.org/Calendar/ https://wiki.gnome.org/Apps/Evolution/ https://wiki.gnome.org/Apps/Evolution/ https://apps.kde.org/merkuro.calendar/ https://apps.kde.org/merkuro.calendar/ Planner/Planify is an all-around decent to-do list/calendar app, kinda like Things for MacOS. From there, you could also check out GNOME and KDE's default calendar apps to see if either of those do anything for you. Finally, if you want all the features (and a less-maintained app) then Evolution is the old GNOME groupware app that does scheduling really well.