Converting a Steam Controller dongle into a SteamVR dongle
Another way to get more VR dongles if you have unused Steam Controller dongles laying around!
WARNING: Messing with firmwares can potentially result in bricks, be wary and double check your dongle is supported as per the requirements! Furthermore, please understand that this is not supported by SteamVR officially!
The application flashes all dongles connected to the computer at once, so be sure you unplug any you do not want flashed!
Guide is found here
(for backup purposes, the linked repo including the docs are archived here, credit to "ykeara:")