You can add support for new devices, I haven’t needed to do this but here’s the doc’s
Two caveats worth mentioning.
First, zigbee2qtt runs on Stretch only, if your OH is on Jessi then then you’ll have to reinstall. Alternatively, you can use a different RPI for the USB stick.
Second, the USB stick has a limit of 35 devices. For the price, around $7, you can buy several and use a second RPI to both add devices and extent your zigbee range.
Here’s a how to tutorial on the forum with a few examples.
