Almost all public companies have shareholders from all over the world, including China.
While Opera might not be a Chinese company in the strictest definition, over 50% of Opera's shares are owned by their Chinese parent company, and by all accounts around 80% of the shares still seem to be in control of the Chinese conglomerate that owned Opera before it went public.
You might want to stress that Opera is Chinese-controlled then; which is different from Chinese-owned.
(Eg Google is controlled by its founders, who still have the majority of share voting rights and are in power as executives. But it's not majority owned by them anymore.)
Did Zhou Yahui buy a bunch of shares in Opera? Otherwise, I don't know why he would be CEO of that company (as a billionare). Ok, from his wiki page:
> The next month, a consortium of investors including Beijing Kunlun acquired Opera Software with Beijing Kunlun acquiring 48%, effectively granting ownership to the company (and Zhou Yahui) by majority.[12] Zhou has served as chairman and CEO of Opera since 2016.[4]
> In 2016, Opera was acquired by an investment group led by a Chinese consortium.[7] On July 27, 2018, Opera Limited went public on the Nasdaq stock exchange, raising $115 million in its initial public offering.[8] Opera is a subsidiary of Kunlun Tech Co., Ltd., and controlled by Zhou Yahui.[9]
So they bought it, and then they sold some of it (that's what an IPO is).
What's important here is the last sentence with 'controlled by', which is in practice more important than ownership.
Opera is a public company. Almost all public companies have shareholders from all over the world, including China.
https://en.wikipedia.org/wiki/Opera_(company) has some details.
EDIT: that Wikipedia article says Opera is indeed a public company, but it's only indirectly publicly traded via a chain of parent companies.