Comparison Different Solutions

	Dashboard	Notification Center	Widgets ($10.99)
macOS	Up to 10.14, Mojave Removed in 10.15 Catalina	From 10.15 Catalina	(At-cost app, Mac App Store (USA))
General description	Great feature that we used as a lot with Clocks and related Weather for lots of cities around the World, some 9 pairs (3 in US, 6 rest of World), Calendar, …	Way more limited compared to old Dashboard but this is what exists out of the box of macOS since 10.15.	Could possibly be interesting. Not yet evaluated too much, DO seem limited in Weather locations, and not sure how flexible in own layout of widgets positions.
Bringing up	F12 key (std in macOS)	Must click in Notification Center menu at top right of screen.	(F12 keyboard is definitely possible)

Dashboard Going Away (2019)

Open “System Preferences” from the  Apple menu
Choose “Keyboard”
Click the “Shortcuts” tab
Select “Mission Control”
Locate “Show Notification Center” and Check the check box
Done if Ok with using “F12” as earlier used for Dashboard. (Preset in macOS 12 Monterey)
Otherwise click to the right of the text to enter an input box, then hit the keyboard shortcut you want to assign to open Notification Center (like fn+control+F8)
Test it out to confirm the shortcut works for accessing Notification Center, then quit out of System Preferences