Is this patent legal?

Let me answer a part first, and judge whether a patent application can get a patent right is based on the filing date. That is to say, although you have not obtained a patent certificate, you have applied for a patent, and selling the product after applying for a patent will not affect your patent application.

In addition, there is no law that products without patent certificates cannot be sold.

Your question doesn't say whether the United States has applied for a patent. If it is, the American patent is in a valid state, then China's products can't be sold in the United States, and conversely, American products can't be sold in China (without the permission of the patentee in the place of sale), because the protection scope of patent laws in various countries is regional, and you have obtained the patent right in China, which only means that you have obtained the right to use the patent in China (excluding Hong Kong, Macao and Taiwan). No unit or individual may exploit this patent without permission, including manufacturing, using, promising to sell, selling and importing the patented product for commercial purposes. The same is true in America.

If you can be sure that this patent in China is the same as that in the United States, you can declare that patent invalid in the United States. Both China and the United States require patents that have not been published at home and abroad before the filing date. Your patent was first published in China, but it is invalid in the United States. As for the "shameless person" you mentioned, you need to know more about it.