Two serious blockers, that should have probably delayed Stream 4K release (and likely led to a number of device returns), have been resolved per TiVo.
First, the rampant HDMI CEC issues are supposedly resolved, along with TiVo providing a first cut and of an Android TV CEC settings screen. Second, the more sporadic screen blackout issue has also been resolved. As such, alongside Channels DVR support and ongoing $50 promotional pricing, this former TiVo customer has placed an order. And hope springs eternal for Stream 4k TiVo Mini-esque functionality, given a sufficiently vague note from TiVo PR.