I've been running home automation 24/7 for few years now, using Mozilla WebThings then HomeAssistant. I indeed selected my hardware to rely on proper standards, e.g. ZigBee, so that I wouldn't have to use any proprietary app. For me it's mostly about resilience, e.g work offline, than privacy but of course I also appreciate that benefit.
... that being said, and I did read https://www.home-assistant.io/blog/2025/09/11/ai-in-home-ass... or even have use a local modal for STT but IMHO it's not good, definitely not worth buying a $4k device for. It doesn't generate good rules, it gets some commands but it's quite basic. So I understand the concept but so far I haven't seen anything good enough to warrant such a purchase for such a very very specific niche. I can imagine literally a couple of persons interested in this but I'd bet they'd also have a GPU laying around that could be available for that too.
TL;DR: technically not impossible, I doubt it's a popular use case.