Foxconn is the world’s largest AI server maker?

Yes, since they produce the most chips for NVIDIA:

In a report on the AI supply chain in March, Morgan Stanley said Taiwanese vendors accounted for more than 70 percent of Nvidia’s global GPU server shipments in 2023, with the Hon Hai Technology Group (Foxconn) accounting for 24 percent of the total, Inventec 22 percent, Quanta Computer 15 percent, Wistron 5 percent, Gigabyte 2 percent, and Wiwynn 1 percent.

https://english.cw.com.tw/article/article.action?id=3692

And they even operate data centres?

They don’t

Sure, once you make the move it’s great. It’s just that it takes time and resources to actually make the move