Back when I was at Amazon they used Anthropic models almost exclusively. Not sure how much that's changed in the last year.

I wonder where the China labs supposedly distilling anthropic models rank among the top customers

true, but it's also super easy to switch models via Bedrock (my harness switches subagents between A\, OAI, Kimi, Grok, etc... GLM 5.3 is locked behind some dumb request system which I personally believe is because Amazon is heavily invested in A\) and you're not locked in with the Claude Enterprise features (i swear to god if someone sends another claude artifact instead of publishing to git...)