I was able to select a preferred hub prior to the new HomeKit architecture, however long ago that was released. Now that I’ve been stuck expecting HomePod minis to process my security camera activity it’s been so frustrating. I sent Apple Feedback well over a hundred submissions complaining about it, called tech support a few times for good measure on top of that. (“I’m doing my part!”) I’d go unplug all the HomePods to force an AppleTV as the hub but then within a day it’d be right back to a HomePod.