You can also include the stick as a secondary on the ST hub, and control the devices through both OH and ST. No need to reinclude the devices. I did this when I migrated. I would build a rule in OH and then turn off the one in ST, until all of the automation was moved to OH. I then shifted the stick from secondary to primary and turned off the ST hub.
I now use one of these in OH. It is a combo zwave and zigbee (Ember) controller…
If you can find the zigbee network configuration in the ST hub (I don’t know if this is possible), then you can just configure it into OH and it will take over control of the zigbee network.
This is a pretty big thread, but there is a lot of info on the zigbee binding. @chris (the maintainer for both the zwave and zigbee bindings) would be the best person to ask about controller compatibility.
If you haven’t yet, definitely read through the tutorial and user manual…
https://docs.openhab.org/