If you own a Samsung Galaxy Note 9 in USA and you bought from a carrier like T-Mobile, Sprint, Verizon, AT&T etc, then there is a way to fully USA unlock it. Make sure to remove your SIM card and micro SD card before proceeding. Also, make sure to use the original USB-C cable that came in the box so that there are flashing issues with your Samsung Galaxy Note 9.
Keep in mind that this process will delete everything on your Note 9 including all data stored on it.
Step 1. Ensure that you have the Samsung drivers for mobile devices installed (which will also be linked below.)
Step 2.Extract the Firmware Zip (pie, oreo) that you downloaded, Open the modified Odin and click on the BL box, Then select the corresponding BL file. Click the AP box and select the AP file, Do the same with the CP and CSC files by putting the matching file name into the corresponding boxes.
Step 3.Ensure USB Debugging is enabled and then shut down the phone. Then hold (In this order) Volume Down, Bixby, and Power button until you get to the Download mode warning screen.
Press the Volume Up button.
Step 4. Plug in the phone, and check Odin to ensure you see a blue box that says COM (also has a number at the end)
Step 5.Press Start in Odin and wait till you see pass, if it says PASS, The flash was successful and within about 10 minutes your phone will boot into the welcome screen.