I have just finished getting drivers for the Levoit 200S and 400S air purifiers working. My first attempt at coding it up is located at: Hubitat/Drivers/Levoit at master · NiklasGustafsson/Hubitat (github.com).
I don't quite understand how to work with the package manager, so all there is is four files that you can copy into the driver code section and then set up everything. The Readme file will hopefully explain everything you need to know to get it working.
The drivers will only work with the "smart" Levoit purifiers, and they require that they have been set up with the VeSync mobile app, so that they are found in your VeSync account.
Start by copying all four drivers, then add a 'VeSync Integration' virtual device. It will setup a child device for each 400S purifier, and two for each 200S (one for the fan control, one for the night light).