It’s hard to consistently line up the hands across different controllers with the poses the base OpenXR plugin exposes. SteamVR at least supports sending simulated hand poses based on the controller pose and button inputs though the OpenXR hand tracking plugin. Not sure which other runtimes support it though.
The support for the hand tracking extension is very bare-bones in Unreal, and it’s very tedious to use. When I last tried it, you had to retrieve the bone poses from a Get Motion Controller Data node and manually align all the hand bones with the poses. I made some pull requests to make them easier to use with the anim graph editor, but Epic doesn’t seem interested.
There are also some third-party plugins that might help, like this one:
https://github.com/demonixis/FSOpenXRHandTracking
I haven’t tried it though, so I’m not sure how useful it is.