Select note/beat across staves?

In Sib, there’s a simple key command to select a note/beat across all staves (whether there is a note or rest at that beat in a staff, it will be selected). This is handy for selecting before moving or doing something else with that beat across all staves. Since I use key commands primarily in Dorico, am wondering if it has a key command for that?

Not explicitly. Shift-up/down arrow is your best bet. While Shift-L/R sometimes yields an unexpected selection, up/down is pretty predictable.