I brought a very cheap Leap Motion 25 quid !!,with a few scratches on lens not sure if that hindered the Leap but I did have mixed results,I did get the Vive controllers to show up in steam but it was very erratic,used hand gestures for triggers with the steam Leap drivers from Github,and used the same drivers as stated by OP the Leap Orion drivers.
Main problem was positioning of controllers with steam menu and inside games they were all over the place hit and miss if it worked even with leap stuck to front of HMD,if you can get a cheap 2nd hand one go for it but personally I would see how Nolo and the drivers pan out regarding Pimax usage as a new Leap is still expensive to buy.
From experience I can say that the tracking is great (even though their in beta) but you still need bluetooth controllers for the triggers emulation. In the last iteration of SteamVR beta the leap motion controllers became improper recognized…Greg its currently addressing the issue.