First of all, I appreciate all the information in regards to how Android is used in China. I did have a knowledge gap on how Chinese mobile companies used AOSP. And indeed, from the sound of it, losing access to AOSP in a technological sense, is not really a threat.
But I still need to insist on a detail - open source is not equivalent to "no license." Open source software is governed by an open source license (typically some variation of Apache or GPL) granted to users. Like any other license, it can be revoked. If you lose access to the license, then you become subject to copy right infringement claims upon cloning the code. While it means little in countries where the US has no jurisdiction, it means a lot in countries where the US does.
Would companies like Xiaomi, Oppo, etc. risk getting shut out of the US, Europe, etc. in violation of a platform ban on Byte Dance software? Judging by past actions, if the US sanctions Byte Dance, *any* company that does business with it (and which uses any US technology, including chips and other licensed software) can be subject to similar sanctions for violating US export control.
This includes companies that only host the application in China.
This is why having ANY dependency on US software - including open source software - is risky. Of course, you could make the argument that if the US wanted to target a company, it can come up with any reason - or no reason at all - to ban it across all friendly countries. Indeed, the US could create new laws just for that purpose, like with the RESTRICT act. But as the laws stand today, it is the use of US technology that puts you at risk of export control sanctions internationally.
