From all appearances, Orbi does have a "Quality of Service" (QoS) mechanism. There are numerous parameters in the firmware that have "qos" in their description. The question you are probably asking is, "Can the User influence the priority given to devices?", and the answer as far as I can tell is, "no".
The "Good News" in the discussion is that many "Internet of Things" devices have very low bandwidth requirements (switches, thermostats, sprinkler controllers, garage door openers, front door locks, alarm systems,. etc.) Even things like security cameras have only modest bandwidth needs. When I stream a security camera on my smart phone, for example, the bandwidth is under 300K and that is going "out" of my Orbi, so it does not compete much with streams coming "in".
