Someone more skilled about python environment may be able to help you further, I can’t.
Reflashing would loose any data on Jeston (you may save important work if any before), but it can save hours of debugging if you’re unsure about what you’ve installed and custom configured.
From a clean jetson install, using one of these scripts should be ok for both python2 and 3:
https://github.com/AastaNV/JEP/blob/master/script/install_opencv4.5.0_Jetson.sh