I know it's not always recommended to work with Array formulas. Not sure if I can do it in another way in this case.

But I encounter another kind of difficulty: Once I have the formula, it must be copied and pasted in many cells.

Is there another way to do this 'paste first, then F2, then Ctrl-Shift-Enter and then the next cell' ritual?

The normal shortcut for applying to more cells in one time (Ctrl+Enter) doesn't work this way.