KIWI design Tracker Straps and Belt for Full Body Tracking VR, Compatible with Quest 2 and SteamVR, Upgraded Palm/Foot Trackerstrap Accessory Fit HTC Vive Tracker (Trackers NOT Included)
MixedVR Vive Full Body Tracking - complete setup guide - YouTube
ImmerSight Positional Tracking for Any HMD, Solution for Oculus Rift?
Front-facing Camera and New Positional Tracker for Oculus Rift Shown in Leak – Road to VR