Of course you're correct re: laptop and aux kb - I was thinking of "seat" (and multiple seats) being: "Wayland seat refers to one 'seat' at which a user sits and operates the computer."[0]

So a keyboard being attached to a seat, whose input might be associated w one active window, while another kb is associated with a different seat and different active window. Perhaps I'm just overthinking it.

[0] https://wayland-book.com/seat.html