Japan is also pretty full on in their foreign recruitment. I saw a tall black lady playing for their 3x3 basketball team.
China is going the way of
recruiting foreign citizens with chinese blood from either parents. some of them switched citizenship for various reasons.
Some high profile ones I know
Hua tian
British chinese
Eileen gu
American chinese
Nina li
Canadian chinese
I think these three are not strictly "foreign citizens". If you take a look at their ages of representing China, you will know that they are all Chinese citizen by birth, not foreign citizen switching side.
Chinese citizenship law stipulates that a person born to one Chinese parent is Chinese citizen, regardless if they are given foreign citizenship automatically at birth. If the person had such foreign citizenship at birth, the person need to make a final and legal claim on his/her Chinese citizenship before age of 18, therefor renouncing the foreign citizenship because China does not recognize duel citizenship.
Also, due to the policy above, a person's foreign citizenship has no legal significance as far as China concerns. Their difference to a Chinese in China is that they need to say it loud at age of 18.
Hua Tian had British citizenship due to his mother, but he renounced it at the age of 17. Gu Ailing (Eileen Gu) renounced her US citizenship at age of 15. Zheng Ninali (Nina Schultz) was reported by Canadian media as having applied her Chinese citizenship at 19, this is only the date that the news is made aware of, not necessarily the real date that she did. I am sure if the athlete are eligible and the government really want, it will be arranged that the paper work is well prepared ahead.
There are many others in Chinese football teams who may be real foreign citizens that is they never had the Chinese citizenship or they did not make the claim before 18. But I did not dig the details.