Yes, as long as all of them are running the same VERSION of firmware, even if a different hardware.
So a FOCBOX 1.6 and a Unity and a VESC 6 Mk5 could all work together if, for example, all 3 of them had version 5.2 firmware, but each with their different hardware build.
But do keep in mind it sends the requested current over the CANBUS, not the requested throttle percentage. It may be a good idea to use the ESC with the highest set motor maximum (& minimum) current as the master ESC on the CANBUS.