Yes, I'm using a Tablet Samsung S7 and Android phone.
With phone i've resolved using circular gif animation, with Tablet (with keyboard and touchpad connected) i can use the same gif but i'm curious if it is possibe to use a code like "MainForm.RootPane.MouseCursor = fx.Cursors.WAIT" with B4A.
There is no mouse cursor in Android unless you connect a mouse.
If you want to show a custom progress indicator then use B4XLoadingIndicator or AnotherProgressBar from XUI Views or one of the other similar libraries.
You can combine it with B4XDialog to show it inside a dialog.