"Partnering with Tesla to apply their megapack storage"
In other words, getting enough information along with the purchase that they can build their own and thanks to cheaper batteries in China be able to sell a megapack clone for half the price in a few years. The US and maybe the EU would block or tariff it, but they'd sell it to the rest of the world. You'd think Musk would know, you never "partner" with China in tech, they are just looking to take over your markets.
With renewable power growing massively worldwide, but especially in the third world, utility scale battery systems are going to be in high demand, and China will be selling them.