Anthony Thanks for the speedy response, wow!
Sure, seems really cumbersome to attach a photo in this forum but basically the hierarchy is
Unity ScrollRect+RectMask
ResponsiveContainer w/ Group Content in container and expand
Content which is dynamic
The other issue w/ this workflow (which I feel like is probably the most common mobile layout for displaying data), is that the container is either "OnUpdate" or "OnChange." OnChange will change if you add/remove items, but won't update automatically when you change screen sizes (which sucks for actually developing and testing). I feel like you need to attach to onWindowSizeChange as a separate option.
Also, when you, say, add an item in a scrollRect, the actual yLocation of the container within the scrollrect changes instead of staying fixed at the top (if its contents are aligned at the top). Not sure if this is a Unity issue or on your end.