Part of the reason I haven't yet moved away from Google services on my pixel is because of the call screening and anti-spam features. I screen unknown callers pretty much all the time so Google is listening if they call me anyway. I'm fine with that, knowing A. That the callers get a heads up that they're talking to an AI and being recorded and B. That the ones who are human and trying to scam me generally don't call back once they know the line is being actively recorded.
There's no feature parity for this on any of the roms I would move to. Taking it a step further is unnecessary for me, and I'll probably opt out. But I can fully understand why someone might want it (for their elderly family members for instance).