I want to know when the user moves focus to a new row - I intend to use that to select this row and to perform some operations on an adjacent grid.
The majority of things are possible through templates right now. You can put in the desired template (editor, row, cell, header, whatever you need to capture events from) and add the desired handler to your own DOM element. Then, you can alter the grid, if needed, through its state. If you need the row data item - it is available in the templates related to the data rows. If you need adjacent rows models - you can get them from the sorted list of grid data when you use its OnRead event - you have the current row and you can get a previous/next one as needed from that list.
That said, I am keeping this item open (status "Unplanned") so we can still gather any feedback and its popularity and what the community thinks, and whether it will be a meaningful addition to the component.