[cphoover]

Is all audio up to “Alexa” still processed on device?

[Cthulhu_]

It should, but as far as I know you have zero guarantees about that. I just hope there's privacy organizations and / or hackers that continuously verify these claims. Of course, Amazon can push an update at any time to change this, at which point it'll be too late to think "hmm, 1984 warned us about this".

[iLoveOncall]

The insane cost to process all this is the guarantee you need.