Ask Lemmygrad

About Google, they still have a (valid?) ICP license ICP证合字B2-20070004号 registered to their company in China 北京谷翔信息技术有限公司, and ICP record 京ICP备13004732号-2 for google.cn that was last reviewed in 2020.

The following are basically just the .cn mirror versions of the .com counterparts with some minor differences (like hints for links that may not be accessible in China).

https://developers.google.cn/ https://source.android.google.cn/ https://developer.android.google.cn/

Microsoft's Bing (and other products) is legally operating in China at https://cn.bing.com (registered to 微软移动联新互联网服务有限公司), and they display the relevant licenses at the bottom of the page:

You can look up the ICP records of domains operating in China at https://beian.miit.gov.cn/, a handy service provided by the Ministry of Industry and Information Technology, either search by company name, domain name or ICP record.

As for why no American social media services are operating in China, they just can't handle the regulatory burden of upholding socialist values.

Edit:

Just remembered that Microsoft's Skype is still working in China, that counts for American social media... or at least American chat software. Discord is partially blocked (see my definition of "partially blocked" in my main comment here: https://lemmygrad.ml/comment/3886144) but I couldn't get it to work without a VPN because they use WebSocket. Matrix works but matrix.org is partially blocked, so you'd have to use other non-blocked homeservers like genzedong.xyz.