That is an excellent observation and thanks for sharing.
I will go to the local nursery and look at ferns. I saw a bonsi grouping there I'm sur they also have suggestions.
First thing is the Nanna has to peek out of the soil.
No hostas of anykind are showing yet. Maybe another week.
Geez Jo - you're looking for stuff for shady type environments. I agree with the ferns. Maybe some violets for color. Heucheras are nice too. I'd also add epimediums but they may be to large for your plans. Plus we don't know the size container you're going to use. Definitely have to look at the alpine plants. Most of the ones I think of spread which would overwhelm your container.