This is only available for the Emblaser because it’s required for the machine to work properly. On a Ruida you just use the buttons on the machine to move the bed up or down and manually focus that way.
A Ruida controller typically doesn’t home the Z axis like the Emblaser does, so using absolute positioning on the Z doesn’t work until you focus it, in which case you’ve already set the Z height, so there’s no point in having this feature on that hardware.