i think you can already accomplish a lot of these things just by doing some custom coding using the existing API. i don’t have the energy to work specifically on any of the things you’re describing, but i’ve made things in the past that are similar to what you’re describing, and you’re welcome to adapt the code as you wish.
trends (bar charts and data tables):
no bar or pie charts, but what about a table or sankey diagram?
or a packed circles diagram?
… oh, and you didn’t ask for it, but here’s a quick way to display top observers in a place:
i’ve made other things, too… i forget what they all are, but you can find most of it in the Github repository.
if you search on the forum, you’ll also find things that other people made. for example, observation streaks:
and kueda made this, too:
url: http://kueda.github.io/inat-days/
code: http://kueda.github.io/inat-days/