When you walk through the pairing process using the Samsung SmartThings app you are asked to provide a Hue hub or a Hue ID. So you can’t pair Hue bulbs directly like Ikea bulbs (which work ok on my SmartThings hub very well). Again: this is not my understanding of a standard.
I know that I could use an USB dongle. My OpenHAB is running in a Docker container on a NAS. I didn’t want to put effort in passing an USB dongle connected to the NAS to the container. This is why I preferred an IP connection rather than a serial or USB connection.
My conclusion: be very careful if a vendor claims to be “ZigBee certified” and develop your own best practices.
Greetings
Reinhold