Yes, to all
But
If you own the original, 1st gen Apple Magic Mouse or Magic Trackpad, scrolling and gesture features are NOT supported in iPadOS 13.4.
Sorry.
The Apple original, 1st gen Magic Mouse will still work and do things in iPadOS 13.4 or later.
The 1st gen Magic Mouse will still work as a traditional two button mouse, without a scroll wheel .
The right side of the mouse can be customised in accessibility menus; And the primary button (left) can be set with a long press to mimic right click on hidden menus.
Combined with the new screen cursor ( customisable in Accessibility ) and the Hot Corners feature ( found at the bottom of the assistive touch menu and customisable, as well) you can get a fairly functional experience.
For scrolling, Its click and either drag with a quick release under the inertia or click and hold on the on screen handles and pull in the desired direction
In some apps, double clicking and holding will initiate screen zooming.
Any third party mice will have general support.
Third party mice features may or may not work or fully work with iPadOS 13.4.
Best of Luck to You!