I guess this doesn't need to be listed explicitly here? It's a normal Figure kwarg anyways, so documented there; if anything we may rather want to promote the use of constrained_layout?

Sure, nothing really has to be listed explicitly here. All the arguments here but one are indeed duplicates of figure.Figure.

I am fine with tight_layout here, but should also add constrained_layout (can be a diff PR). The sphinx link below needs to be fixed (leading dot?, I really find sphinx documentation to be hard to make valid cross-references for).

re: sphinx references: any reference to something not in the current module needs to be prefixed by a dot. Possibly with the module name in front to disambiguate further (e.g. between .Axes.plot and .pyplot.plot, otherwise sphinx reasonably complains that it doesn't know which one to use), but not necessary if there is no ambiguity (e.g. .Figure). What gets printed in the rendered html is what you put between the backquotes, minus the leading dot, unless you add a tilde in front of it, in which case all the context is stripped so e.g. ~.Axes.plot and ~.pyplot.plot both get rendered as plot.
(This is made slightly more complicated by the fact that often we have docstrings that are originally defined in one module but end up also in an object defined in another module (via inheritance); sphinx is not able to follow that and will complain if the inherited docstring "wanted" to refer to objects in the first module without using a leading dot.)
Also anything referring to something not in matplotlib at all (i.e. numpy, etc.) needs to be fully qualified.