Any good calendar app in Xubuntu?
You may want to try GNOME Calendar.
sudo apt install gnome-calendar gnome-online-accounts
You can sign in to your Google account in GNOME online accounts, and sync it with Google Calendar.
Image source: https://apps.gnome.org/app/org.gnome.Calendar/
It does not run other GNOME apps in the background, and consumes <100 MB memory, and is not very heavy.
