vMix does have built in PTZ control but it is only available in the 4K version or higher.
We do have a free camera control app that you can use alongside vMix to control the cameras.
The interface should be very similar to the control plugin you were using with OBS.
You can download the latest version of the Desktop Control App (PTZOptics) here.
Low-budget church setup. Single PTZ camera (SDI) and we are currently are using OBS with the PTZ camera controller plug-in to stream.
If I switch to vMIX, is there a plug-in for that as well for camera control? We will be using the "Basic" level of vMIX.