[OutOfHere]

I think the answer is rather simple and boring -- only the CPU type commonly used in cheap cloud machines counts. This still is x86 only.

The homes at home, such as by Apple, don't count for serious workflows that must run reliably.

[microtherion]

Personally, I love synthesis that can be generated on the client machine, in real time. For some applications, like screen readers, this is a really important feature.

Of course, the big interest these days is in cloud based assistants, where synthesizing on server and piggybacking on the rest of the answer is quite reasonable.