If anyone really wants this functionality they can just use HomeBridge or Home Assistant and have the vacuum show up as a couple of on/off switches.
Native support is always nice, though.
I'm guessing that only new products will be natively supported? iRobot probably won't do that for all of their products from the last 5 years or so. Their app alone is too much dependent on external servers and I guess that most likely they won't qualify for HomeKit certification.
At this moment I use HomeBridge to monitor the status of each Roomba. Our living room Roomba usually runs at night and the lights will turn on when the Roomba starts a cleaning job and turn it off again immediately after it's finished. I wished that it could monitor the actual location/room too, to let the automation know which lights to turn on instead of the whole floor. So I'm hoping that HomeKit will support room detection, because HomeBridge with all the available plugins doesn't or fails easily.