Since there is no proper information about unlocking the bootloader for the newer versions of Oneplus Nord 2, this is how I got it to unlock and actually work.
For my system it did reset the device, clearing all the files and factory restoring the device, just make sure to make a backup before you do anything.
Just like any other post, no warranties or anything, this is all at your own risk.
1: Make sure to enable OEM unlocking and ADB Debugging in the developer options
1.1: To have these options, first go to About phone > Version
1.2: Keep tapping the "Build number" to unlock the developer options
1.3: Navigate back to settings and open Additional Settings. There you will find the Developer Options.
You have same issue that adb is detecting phones but fastboot not?
There is no installer by google. You just replace files for updating.
For first make sure CMD doesn't find multiple locations for ADB. Type in CMD where adb. Be sure that it finds correct folder where is platform tools ver 31.0.3!
If it's wrong then you need insert new Path in system variables or changes whole folder where 'where adb' indcates. Also double check that oem unlocking is enabled in developer options on phone.
This is my CMD exaple: