I guess with “cross-filtering” you are referring to the feature where you stay on a dashboard page when applying filters? That’s slightly different from a drill-down into an underlying question where you bring some filter parameters along with you on the navigation, then can add more filtering to refine further.
Metabase does have filtering on dashboards — but currently in a form where you’d have to pick your filter criteria in the drop downs — you can’t do it directly on the visualizations as you show above.
Technically Metabase employs the dc.js and crossfilter libs (those pages have demos similar to your example above). Here’s a search pointing to a few places where crossfilter appears directly in the codebase.
So it appears your proposal would build on the existing dashboard filtering feature but enhance it with an (optional?) alternative way to select. One UX thing that would need figuring out is that Metabase already use mouse clicks and scrubs on the visualizations to do e.g. drill-down. (On an impulse: Maybe it could simply just be added to the current menu that pops up when you click to focus on a series or point? - guess a prototype could verify if it’s viable).
I’m sure the Metabase core developers already might have considered crossfiltering. They are quite committed to keep “The Zen of Metabase” meaning they shy away from adding too many user options here and there but go to lengths that Metabase just defaults to the simple intuitive thing (I like that). On the other hand they welcome quality PRs, but keep a high bar to entry. The contributing section in the 
Developers Guide is a good starting point.
Sorry for the lengthy rant 
I’ll stop now.