I thought CXMT already have plenty of capacity - Apple are currently talking to the US government for blessing to buy from them.
Other manufactures like Micron do have aggressive expansion plans, but fabs take a long time to build and bring online - multiple years.
CXMT is sold out too.
https://www.guru3d.com/story/cxmt-dram-capacity-reportedly-s...
There is TWSC: https://en.twsc.com.cn/
Traded as CUSU for end-users: https://en.twsc.com.cn/enCUSU/index.html