It's a regular DS with twice the eeprom (512 KB), containing the Chinese firmware (which replaces Japanese with Chinese, has simplified hanzi in the firmware's font, has some data moved around, has a different software-readable model number, and has
some more space for the system configuration)
Chinese games have a simple region lock, also simple to patch out, that artificially requires a Chinese DS - the console itself is region free as ever
Very few games were ever made for Chinese DS and 3DS, probably less than 20 each generation - it has to do with game consoles having formally been illegal for most of this millennium outside of "educational products" (think of all the keyboard famiclones - but what did they pass most of those DS games as?) and probably to competing in the country that invented flashcards
And yes, Chinese 3DS is the least featured region with basically no online services, the system apps version (the part after the "-" in the version number) lagged behind until the security theater of 9.x and newer
IIRC:
Korea - no theme shop
Taiwan - no themes, no miiverse, commercial disaster (was invented
later to replace official imports of Japanese models, incompatible of course with those, lack of releases, Japanese models remained market leaders - if you search "taiwan 3ds" on google images and look at boxes, you can see "Ct version" and "Jp version") -- coolest home menu
China - all of the above except no official imports, no eshop, no amiibos
