Do you think the basic physics and sensor tolerances would let you go to 10^-2 meters if the environment (e.g. wifi station placements, location of RF-interfering elements) was designed by you?
If you want high performance indoor positioning , look into 5G carrier phase positioning which claims cm-level accuracy. Fuse that with IMU and optical sensing and you certainly should get decent results
I've personally used one of these before in a performance where you needed individual based tracking, the chips were active UWB radios and sensors were placed and calibrated around the stage, I believe it was < 10cm accuracy and quite an interesting sensation to walk with lights following you perfectly and quickly.
