I think I know what the issue is with Leap. So some reason installing the driver at https://github.com/cbuchner1/driver_leap doesnt actually install it in the SteamVR path, so..
copy the "leap" subfolder from here:
C:\Program Files\SteamVR Leap Motion driver\
to:
C:\Program Files (x86)\Steam\steamapps\common\SteamVR\drivers
Then launch SteamVR and the hands will be present