I'd be curious to see an estimate on the google side.

Here are some real rough estimates in Apple's ecosystem:

For macos alone the install base is something like 110-130 million, and only Apple Silicon macs can run the new model, so maybe 45 million active macs are updated to macos 26 and can run their model.

There are a bunch of details but of the iPhones out there that are new enough to run Apple Intelligence and have iOS 26, something like 220 million can.

For iPad same conditions but for iPados its something like 60 million.

So, something like 325 million active devices are out there ready to run LLM completion requests.