I started to make a shiny app to help beginners learn dplyr, based on Jesse's tweet (with her permission), but stopped when I heard RStudio was developing TidyBlocks.
current status:
At the moment, the data transformation works by creating a string to represent each action, putting them together in the dragged order, then parsing and evaluating the combined string. A few verbs are supported, but the only arguments accepted are column names. For some verbs, the formatting only works with one column right now.