Do we need #AdwLeaflet:[vh]omogeneous-unfolded?
See libhandy#188 (comment 1048706) and after that.
I personally don't see compelling reasons to have that API. All its uses can be safely replaced with
GtkSizeGroup, so it's a convenience API. And convenience API implies it's a common enough thing to do that you might want a helper.
However, is it actually common? Yes,
GtkBox has it, but
GtkBox is a much more generic and often used for things like groups of linked and homogeneous buttons, while leaflet isn't.