I used the shift+s pie menu → Cursor to Selected in edit mode to snap the 3D cursor to certain vertices and then back to object mode, right click for context menu → Set Origin → Origin to 3D Cursor. This way I have the object pivot so I can easily rotate things. Did this for both the door and the handle.
The handle is parented to the metal plate which is in turn parented to the door so it moves with the door. And the same with the door to the frame so it’s easy to move around as a unit.
Just realized there’s no handle on the inside. I guess there’s no getting out…
Edit: Also rendered the animation in PNG format and then dragged all the files into ScreenToGif. Adjusted the delay between frames to 41ms which is roughly equal to 24fps; the same as the animation settings I’m using in blender.