Work and Language in China
First of all, let’s put your Mandarin abilities in perspective. Unless you are some type of language genius, your Mandarin is not going to be as good as the people born and raised in mainland China.
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There are lots of Westerners with great Chinese language abilities now too. For example, the current generation of Canadians includes Euro-Canadians that have learned Chinese in bilingual schools since Kindergarten, as well as enough Asian/white ‘halfers’ to be considered an ethnic group of their own - they’ve had the chance to use Chinese & English in home and at school their whole lives.
Chinese workers are extremely competitive in just about every field too. I can’t think of any fields of work in which they aren’t competitive. Regardless of which field you’re in, Chinese are competitive and generally a lot more aggressive at career & business development than Westerners.
Your main assets are your English language abilities and your ability to understand and communicate with Westerners on a deeper level.
With these, you can get a job as an English teacher or in some type of client-facing work, with the clients being Westerners.
Plus, you probably have some additional skills in certain fields. Those could be essential. For example, let’s say you want to work in a company that does robotics engineering. You could use your language & communication skills plus a relevant technical education to attain a job as a liaison with American companies.