The problem is that the internal processes taking place in China will not allow to make the crypto market open for all, i.e. for citizens. The only option is to use cryptocurrencies to circumvent sanctions. How effective this step will be, we can only try to guess. Sanctions are an unpleasant thing, and China is very afraid of their strengthening, which means that it will take risks only in case of "vital necessity". Whether China needs it is a rhetorical question.
Cryptocurrency has been mentioned as a way to avoid financial sanctions. For example, Russia once wanted to use crypto to pay for oil bills but was unsuccessful. At present, China does not have this goal because it is still free to use global financial services.
I think China may change its views and regulations on crypto if it wants to keep up with the world in the crypto wave and collect huge tax revenue from this market. Another reason is that investors are looking for BTC and crypto to diversify their assets, putting indirect pressure on the government. I think in the future, we may see crypto legalized again in China!
The fact is that for a NOT-ISOLATED economy to work, you need the processes of exporting and importing goods. This means that in order to interact with the "external economy", China needs means of payment that will be accepted there. In the EU, the US, in short, the Western market. At the same time, we should not forget that China depends on Western technologies at least.
This means that in the example you gave about sanctions - we are talking about mutual settlements between the same countries (sub-sanctioned/void countries and the like). And the question is: what difference does it make to them, if in fact they will switch to almost barter schemes? The unit of settlement can be bitcoin, cones, Kauri shells, .... ...anything, because it will be a turnover of goods in an isolated environment.