Just as a nitpik - there are Azure regions in China. But it's complicated.
Microsoft Azure operated by 21Vianet (Azure China) is a physically separated instance of cloud services located in China. It's independently operated and transacted by Shanghai Blue Cloud Technology Co., Ltd. ("21Vianet"), a wholly owned subsidiary of Beijing 21Vianet Broadband Data Center Co., Ltd..
The real Azure and AWS is accessible in China, too. In fact, that's the easiest reliable way to bootstrap from "I'm in China and have no censorship-circumvent tools" to accessing the real Internet.
Azure defintely operates in China https://www.microsoft.com/china/azure/index-en.html
Twitch works from time to time depends on which unfortunate AWS IP address it streams on.
Zoom isolating China as a standalone market
Apple iCloud has the local version
For Steam, there's a HUGE Chinese player base, but steamcommunity.com is blocked
Some of the websites you mentioned were "collateral damange" https://en.wikipedia.org/wiki/Collateral_freedom