Not sure if you're joking, but of course they already have:

https://www.seeedstudio.com/xiao-series-page

Half joking. Point is there is enough alternative offerings, including ones from China. Personally I've never used Arduino and their IDE. Was doing C/C++ on Teensy and some other MCUs and that worked just fine for my projects

I can't speak to all their products, but their nRF52840 offering is very good for those who want to build BLE based devices.