You ask whether the Uighurs suffer as much as Meghan Markle, since a lot of people speak out about the latter and not the former. I'm not sure how accurate a comparison this is, however.
On the one hand, you have communal suffering (if that is an appropriate term), where a community of people are being targeted by a state government and physically tormented over their ethnicity and faith. On the other hand, you have personal suffering, where an individual is being targeted by a national press and psychologically tormented over their race.
I think that the two forms of suffering are different in the sense that one is looking at large-scale persecution of an ethnic group, whilst the other is looking at a witch-hunt by such a powerful and influential institution (the press, not the royal family) aimed at a single person. As a result, I do not think that the "x is more spoken about than y" argument is productive, since here it is comparing the popularity of apples to that of pencils.
At the same time, there are some similarities. The treatment of Uighur Muslims in China and the disappointing international response shows a lack of regard to the welfare of people who follow Islam (read: are 'different'). Likewise, the treatment of the first black modern royal in Britain at the hands of popular press and the failure of the royal civil service to protect her from abuse is telling. I don't think that race is insignificant here; concerns about her future baby's skin colour, and the difference in how her and Kate were treated in the press when the only actual differences are their skin race and nationality, show that. The importance here is not just that it is a high-profile example of implicit racial discrimination, but it speaks more widely to the problem of racism in society, when an aspiring person is savaged for not being white.
In short, one does not have to choose to focus on or be concerned by the treatment of either the Uighurs OR Meghan. It is possible to be outraged by each on its own merit. I spoke about Xinjiang; I did not write about Yemen, or Darfur. It does not mean that I merit the suffering of the Uighurs over that of the Darfuri or the Yemeni peoples. Focusing on one instance of abuse does not mean you invalidate all other cases.
I hope that answers your question.